Let's not get carried away here. India or the Far East would be really pushing a fine TL into ASB status, likewise conquering the British Isles.
You CAN be reasonable and still have some amazing changes in the world. At least, that's what I've heard.
Possible changes:
1) The Little Ice Age is unavoidable and renders Greenland useless for settlement purposes, although a single fortified base could be justified. Nonetheless the Scandinavians have a shred of awareness regarding North America with grape vines and huge trees perfect for ships and so forth. Have an effort made to shore up Iceland, perhaps it becomes the holding of a loyal but less prominent family willing to settle for the title of earl with an unusual degree of independence?
Independent lords might be especially eager to expand westward.
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I]With the re-establishment of Regular supply ships... the Eastern settlement probably gets a longer life....but agreed thaat once things get so bad that the Western settlement has to be abandonned they will move back to Iceland or even Norway....others will congregate for a while in the Eastern Settlement. As conditions worsen someone will go looking to see if the tales of Vinland are true...once rediscovered, say in the '40's or 50's most of the Eastern settlement will re-locate to Vinland (where ever anyone thinks that actually is ....for now we will say northern Newfoundland and the straits of Belle Isle, but anywhere on the Island will do) That leaves only a small fortified outpost to supply the ships plying between the waters of Iceland and Newfoundland. The whole expedition is likely to be the idea of Greenlanders returning to Iceland and drumming up support there for an Icelandic voyage of re-discovery.
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Once the great fishing resources off of Canada/New England are found it is certain that the Scandinavians will follow. Circa 1630 Plymouth had less than 300 people but more than 10,000 were off the coast most of the year. Once the Scandinavians find such a valuable item(food and trade) they inevitably start trading with the natives and settlements will be sure to follow.
Since it is believed these fishing grounds were being used by 1472 have the date advanced by 20-30 years. By 1460 the king becomes sufficiently aware as to start to encourage trading on a larger scale, no doubt a few people have already set up shop, the fishing fleet being something of a captive market when the choice is purchase X or go all the way back to Europe for X.
Once the Puritans got going they were able to successfully go to 10,000 people in less than 5 years so why not a New Scandinavia by the early 16th Century and a quarter of a million people by 1600?
Isn't that pushing the population a bit...Scandinavia doesn't have that many people to populate the place...though I suppose they could recruit colonists from the Hanse cities
Hmm, if the Native Americans get hit by the European diseases a generation earlier they MIGHT offer more resistance to the Spaniards...alternately the Aztecs and Incas might not be such glittering prizes.
It will be the Eastern Woodlands (particularly in the NE...but the SE as well as it filters out from the areas of first contact. )peoples who get hit first...and we are talking probably a century ahead of Otl here... I am not sure that the deseases would spread so rapidly from that area to the Mesoamerican cultures....How much contact was there actually between these areas? Would the desease vectors actually die out before they travelled that far. The whole Dawnland and lower St. Lawrence could be decimated...but would the Scandinavians be able to emigrate and fill the gap before the natives recovered ( would the incentive actually be there...probably only sparsely settled trading outposts at best...... on the coast probably they will be more densely settled....... but not in the interior above Montreal or beyond the Appalachians. A hybrid Scandinavian version of the Metis say. Though I espect the Huron/Iroquois peoples will still be predominant.
2) Going eastward the Republic of Novgorod was an old trading partner doomed to fall before Moscow. How about a little support or simply have a fairly large area including the Kola Penninsula being absorbed? Likewise when the Teutonics go down, the Scandinavians should be there.
Let them offer protection to the Grandmaster of Livonia instead once the Grandmaster of the Teutonic order becomes a vassal of the Poles. Kurland and points north, ends up in some kind of relationship with the Scandinavians that way.
Incidentally the Poles absolutely hated the Teutonics and with very good reason. Perhaps if Kalmar actually helps the Poles a long-term relationship might spring up?
This would actually be a good avenue to pursue....if your looking to contain the future growth of Russia into the Baltic region at both of their expense. Mind you that is along way off... The time of the troubles will be soon enough to consider options like this...but who is to say they occur now.
3) Bear in mind that to a large degree Holland was, quite ironically, the sole long lasting creation of Philip II and the Duke of Alva. Without the Hapsburgs and the effects that several generations of war had on Holland there is every reason to believe that Holland would be a very different place, or, more likely, a scattering of many smaller places. No colonies for Germany-to-be but that just leaves a vacuum to fill, doesn't it?