It is worth noting that Dutch culture is vastly more similar to Anglo-Saxon culture than Swedish culture.
True. It's also worth noting that New Netherlands was hardly a "Little Netherlands". The Dutch West Indies Company wasen't exactly restrective about the ethnic composition of their main settlements, and there were quite a few Germans, Frenchmen, Englishmen, Scots, Jews, ect. mixed in; proporitionaly far more than the non-Franco-Europeans of ITL's New France. That makes the population as a whole easier to assimilate due to the lack of a cohesive identity among themselves... though New Sweden would also likely have fewer locals in need of assimilating. Alot depends on how concentrated the Swedish population stays: concentrated in a number of cultural strongholds along the St. Lawrence (Or whatever they call it), they could retain their distinct identity rather easily. On the flipside, though, it would make it incredibly hard to resist encroachment on their claimed territory by the Hudson Bay Company's agents/forts/settlements in the North, which could lead to a greater chance of friction with the English. They'd need to put in alot of effort to stregthening the native polities to the point they could effectively buffer the Swedo-Finnish "Core", which isen't good for fully assimilating them (in return) in the long run.
I think I'm leaning towards the sentiment already expressed here - "if Quebec was in Swedish hands - a Minor Power, and not French - a Great Power" - would the UK had bothered in taking it at all?
Well, there was a period Sweden would be seriously be considered among the "Great Powers"; during the 1600's they were certainly more than capable of projecting their power and influence to fields near and far and make major strides in administration, proto-industry, the arts, ect. and dominate some key routes and areas of commerce. But they are less likely to naturally gravitate into the kind of long-standing rivalry with Britain due to differing areas of interest (Sweden needs to secure its south and east by nature of its geography to protect its Baltic Sea "core", so Germany, Poland, the Baltic States and Northern Russian affairs will always be prioritized over the Atlantic) so conflicts that would result in such a taking are probably not going to happen.
It's true that the French state was quite ambivalent about mass settlement. It was not just that few French people wanted to move ; the crown was not particularly motivated to recruit and send lots of them, either. There was some recruitment in the 1663-72 period after New France became a royal colony, but then it ended with the Dutch War and never really started again.
My guess is that they would need to discover tobacco, as the English did OTL.
Tobacco would certainly work: if you have a market, it can be a nice and profitable crop the duties of which the French state would see profits from, and can be very efficently produced on small plots that encourage settlement by small groups of laborers (IE: You don't need to develop plantation agriculture, which encourages the adoption of slavery.) However, does that work with the Seigneurial system? Because those French peasent families don't have the money to pay for their own passage, their merchantile class isen't developed enough to sponsor the mass movements themselves (Stronger political control over the economy has its advantages, but dosen't exactly encourage entrepreneurship. France's relative stability and vibrant agriculture/horticulture that strengthened their country nobility shows), and without gurantees of labor/indenture/income (For example, can you mandate the tax on a drying house the same way you could a grist mill? The former is fairly easy to cheat on). France is going to have to put up a pretty hefty initial investment if they want to subsidize the founding of the colony and finance it during its early unprofitable years... without knowing if its going to pay off (Companies like the Virginia Company provided England with her trial balloon, and they went in planning on finding gold for which there is never an uncertainty of a market). And if the project goes bust and the treasury gets stuck holding the empty bag... either the French economy or French budget is going to have to fill it up to everybody in the country's detrement, rather than "scapegoating" the tragedy on merchant companies. The later can and will naturally be replaced, while the former... well, that's rarely a good thing. You'd need to find a way to pay for/justify the granting of land to poor independent settlers for no money down.