BUMPITY BUMP like Trashcan Man...
I feel I need to Ask:
Now that Polynesians are colonizing South America, do you think they could domesticate Cavies, Vicunas, Potatoes, or any other edible animals and plants?
Alternatively, will the Irish or Vikings do a Blitzkreig, or can they domesticate the Grey Fox, camels, horses, or other fauna in America?
I think it depends a great deal on how long those things took to be domesticated in OTL. I'm assuming that this is a time period of only 500 years, so I would guess: for the plants, maybe (although not to the amount of variety as in OTL) but for the animals, unlikely (their generations are too long).
Also, keep in mind that the Polynesians had a few things which were already equivalent, so the question becomes whether they would want to. For example: if you already have domesticated taro, would you really care about trying to domesticate some wild potato species? Especially if that wild species didn't have much 'meat' on it to begin with. More likely, you'd try to create breeds of taro that would survive at higher latitudes and altitudes.
Edit: Sorry, that post was written too quickly.
The time period was 1000 years, but I still think that's on the short side for animals, and a lot of plants.
Also, I should mention that the Europeans also had equivalents which they don't need to duplicate, and which translate towards more variable conditions. I really doubt that they'll feel the need to domesticate any of the plants -- at least not to staple level (they might domesticate more niche stuff -- berries, some wild grasses, ornamental trees and bushes). The wild relatives of our tomatoes, peppers, squash, beans, etc. were probably not as palatable as the food they already have (not to mention most of them grow far to the south of this area).
Here's more rampant speculation:
A lot of the other stuff, maize, beans, chocolate, etc, will be found as almost valueless in its wild form, except possibly for occasional scavenging. It's not like these things grow abundantly throughout the terrain: they share the landscape with hundreds to thousands of other plants within which they may hide. Newcomers will have to try hundreds of different plants before they find anything. Many of these plants are poisonous at worst, and at best merely bad-tasting. Some only show their beneficial nature if you hit upon the exact method for preparing them.
The Europeans will definitely not kill off the N.A. horse. More likely they'll breed it with their own horses (likely not intentionally) to create some new, more interesting breeds (this might reduce the prevalence of any genetic disorders common to these breeds, if there are any).
Camels depends on whether they survive until some culture which recognizes them arrives, and how close they are genetically to the Asian camels. The Northern Europeans will just see them as funny looking, rather disagreeable horses (the only images they'd have of them are poorly drawn medieval manuscript illustrations of animals which could just as well be as mythical as unicorns for all they know).
I don't see the grey fox being domesticated at all (they already had red foxes, and never domesticated them). There might be some new breeds of dogs coming from interaction with North American wolves and coyotes, but nothing that interesting.
They might discover the sugar maple, if the right people get around to it. People from the Baltic tap Birch trees for sap, so the technology was available.
Squash, etc. might be domesticated for the gourds at least.