The way I see it, what the Norse Vinland colonies lacked most was a purpose. Greenland was already on the ass end of the world even by Norse standards, and it was likely considered foolish to go further. Especially when Greenland was already far from an easy place to live. Of course we know now that there was all of North America close by, but at the time they obviously didn't. Even when they found Vinland, the conflict with the skraelings immediately left a bad impression. I figure most people who went to Greenland weren't the stereotypical vikings who were more than happy to raid and fight for something, they were likely those who simply wanted to away from kings, nobles, and whatnot. Fighting with an unknown people over land probably wasn't something they desired.
Vinland also had no significant economic impetuous to be established. Newfoundland while certainly just as if not more livable than Greenland or Iceland, likely appeared to be a forested land little different from Norway. Eventually they would have found Iron and whatnot, but while useful these things weren't in demand. At least not enough that besides semi-regular trips by Greenlanders to get wood didn't fulfill. If there was say, gold, then that would have been a different story. The Spanish and Portugese were at first far more interested in the gold the Aztec's and Inca's were able to provide than they did about all the land available. Even Jamestown was originally based around gold. It was only later they really focused on settling land for the land itself, and that was based around highly profitable pursuits like gold, the fur trade, and cash crops using plantation style methods. With Newfoundland lacking such a draw, it would be a problem.
Two things that could have allowed a Vinland colony to really grow would be racial persecution or political conflict. There had to be a reason for a significant number of Norse to be willing to go on at least a month long voyage to a land they new little to nothing about. A 'it's there, why don't we settle it' likely wouldn't be enough. There would have to be a driving force pushing them to go there.
A simple solution would be to have Eric the Red settle it instead. A 'Snaebjorn Galti' attempted to settle Greenland before Erik. However he failed due to political strife (I admit I don't know the details). If his attempt were luckier and Greenland was colonized earlier, Erik obviously couldn't settle it. However if in 982 during his exile he went there and heard about a land further to the southwest from Greenland fishermen, he would have explored it. So he might have led a settlement attempt for Vinland instead, although he might have called it Greenland instead to draw interest like he did Greenland OTL. Once a population is there, the Norse would quickly find the skraelings weren't a match for them. A party of skraelings might be intimidating to a single ship, but a genuine village/town of several hundreds would be a different question. I'm pretty sure native population of Newfoundland was less than 1,000 total, so even a few hundred Norse could easily gain control over a part of Newfoundland. There, a semi-stable colony likely to last in the long term. It's said Greenland under Erik soon grew to 5,000 inhabitants before a plague in 1002, I think that is an exaggeration, but a population of 1,000 wouldn't be a stretch.
1,000 colonists would probably be enough to make the Vinland colony permanent. Not quite sure what number is necessary to prevent inbreeding, but intermixing with the natives would solve that. So even if the Vinland colony was completely cut off from Greenland/Iceland, it would probably be permanent if no great calamity occurs. A colony of 1,000 in 1000 AD, assuming a population growth rate of 2% (not quite sure what a 'reasonable' growth rate for a medieval society is), would number just under twenty million by 1500 AD. Even without gunpowder, I really doubt an Iron-Age civilization of that population would fail against the European powers after Columbus 'discovers' the Americas.
Really, it wouldn't take huge numbers to have the Norse establish a permanent colony, and a permanent colony would change A LOT even if all contact was cut with Europe.
Of course it is a bit more likely, in my opinion, that a Vinland colony would keep at least loose contact with Europe. In which case a Vinland colony could easily experience a growth from two different events of that general period. If Erik established the Vinland colony in 985 like he did Greenland OTL, then it would have probably been well-known by 995. This matters as Olaf Tryggvason was king of Norway from 995-1000, and had conducted a violent campaign of conversion in Norway. With Erik probably proclaiming far and wide about Vinland's suitability to try and draw colonists, I could see some pagan jarls or Norwegians fearing Olaf fleeing there. Numerous times in history religious persecution has sent some people packing elsewhere. While probably a limited number for the entire Norwegian population, it could cause a rapid bump in Vinland's population and probably bring it to the attention of Norway. The long term stability of this religious migration on the colony would be interesting. Another option, this time without Erik needing to colonize Vinland, would be during Cnut's reign. There had to have been some internal strife. Maybe if Leif had spread his exploration of Vinland around more widely, Cnut could potentially choose to exile dissidents there. Or people who simply wanted to flee Cnut's authority choosing to leave to this land where he can never reach them. Both these options would attract more viking-ish settlers who probably wouldn't shy away from fighting with the skraelings as much as the Greenlanders did.
Really, while I wouldn't go so far as to say it was more likely the Norse colonized Vinland than not like OTL, it wouldn't take much at all for a Vinland colony to succeed. While there were plenty of difficulties and Vinland likely wouldn't have approached relevance even to Norway/British Isles for centuries, all it takes is a crucial difference or two. From the obvious of have Leif make more peaceful contact with the skraelings to a bit more unlikely where a Norwegian King hears about this land from Greenland and decides to try and take it as it would be viewed as an easier target than any European ones.
Vinland also had no significant economic impetuous to be established. Newfoundland while certainly just as if not more livable than Greenland or Iceland, likely appeared to be a forested land little different from Norway. Eventually they would have found Iron and whatnot, but while useful these things weren't in demand. At least not enough that besides semi-regular trips by Greenlanders to get wood didn't fulfill. If there was say, gold, then that would have been a different story. The Spanish and Portugese were at first far more interested in the gold the Aztec's and Inca's were able to provide than they did about all the land available. Even Jamestown was originally based around gold. It was only later they really focused on settling land for the land itself, and that was based around highly profitable pursuits like gold, the fur trade, and cash crops using plantation style methods. With Newfoundland lacking such a draw, it would be a problem.
Two things that could have allowed a Vinland colony to really grow would be racial persecution or political conflict. There had to be a reason for a significant number of Norse to be willing to go on at least a month long voyage to a land they new little to nothing about. A 'it's there, why don't we settle it' likely wouldn't be enough. There would have to be a driving force pushing them to go there.
A simple solution would be to have Eric the Red settle it instead. A 'Snaebjorn Galti' attempted to settle Greenland before Erik. However he failed due to political strife (I admit I don't know the details). If his attempt were luckier and Greenland was colonized earlier, Erik obviously couldn't settle it. However if in 982 during his exile he went there and heard about a land further to the southwest from Greenland fishermen, he would have explored it. So he might have led a settlement attempt for Vinland instead, although he might have called it Greenland instead to draw interest like he did Greenland OTL. Once a population is there, the Norse would quickly find the skraelings weren't a match for them. A party of skraelings might be intimidating to a single ship, but a genuine village/town of several hundreds would be a different question. I'm pretty sure native population of Newfoundland was less than 1,000 total, so even a few hundred Norse could easily gain control over a part of Newfoundland. There, a semi-stable colony likely to last in the long term. It's said Greenland under Erik soon grew to 5,000 inhabitants before a plague in 1002, I think that is an exaggeration, but a population of 1,000 wouldn't be a stretch.
1,000 colonists would probably be enough to make the Vinland colony permanent. Not quite sure what number is necessary to prevent inbreeding, but intermixing with the natives would solve that. So even if the Vinland colony was completely cut off from Greenland/Iceland, it would probably be permanent if no great calamity occurs. A colony of 1,000 in 1000 AD, assuming a population growth rate of 2% (not quite sure what a 'reasonable' growth rate for a medieval society is), would number just under twenty million by 1500 AD. Even without gunpowder, I really doubt an Iron-Age civilization of that population would fail against the European powers after Columbus 'discovers' the Americas.
Really, it wouldn't take huge numbers to have the Norse establish a permanent colony, and a permanent colony would change A LOT even if all contact was cut with Europe.
Of course it is a bit more likely, in my opinion, that a Vinland colony would keep at least loose contact with Europe. In which case a Vinland colony could easily experience a growth from two different events of that general period. If Erik established the Vinland colony in 985 like he did Greenland OTL, then it would have probably been well-known by 995. This matters as Olaf Tryggvason was king of Norway from 995-1000, and had conducted a violent campaign of conversion in Norway. With Erik probably proclaiming far and wide about Vinland's suitability to try and draw colonists, I could see some pagan jarls or Norwegians fearing Olaf fleeing there. Numerous times in history religious persecution has sent some people packing elsewhere. While probably a limited number for the entire Norwegian population, it could cause a rapid bump in Vinland's population and probably bring it to the attention of Norway. The long term stability of this religious migration on the colony would be interesting. Another option, this time without Erik needing to colonize Vinland, would be during Cnut's reign. There had to have been some internal strife. Maybe if Leif had spread his exploration of Vinland around more widely, Cnut could potentially choose to exile dissidents there. Or people who simply wanted to flee Cnut's authority choosing to leave to this land where he can never reach them. Both these options would attract more viking-ish settlers who probably wouldn't shy away from fighting with the skraelings as much as the Greenlanders did.
Really, while I wouldn't go so far as to say it was more likely the Norse colonized Vinland than not like OTL, it wouldn't take much at all for a Vinland colony to succeed. While there were plenty of difficulties and Vinland likely wouldn't have approached relevance even to Norway/British Isles for centuries, all it takes is a crucial difference or two. From the obvious of have Leif make more peaceful contact with the skraelings to a bit more unlikely where a Norwegian King hears about this land from Greenland and decides to try and take it as it would be viewed as an easier target than any European ones.