I don't know about cows and turkeys. If vat-grown meat becomes cheaper than field grown meat then I expect the food chain companies will switch production en-masse and while its likely that some will remain, they would be minority products and possibly different (some of the animals grown these days have been bred for such specific extreme traits that basically they are not suitable for wild living)
This is however not perfect. There are lots of basically subsitence farmers in the Amazon, who do admittedly partake in destructive practises such as slash and burn to create pasturing land for cattle.
They do manage to eek out an existence and support their families from this. Allowing vat-grown meat to flood the Amazon countries with cheap meat will destroy their livelihoods and result in even more people living in extreme poverty where there is not any state protection nets.
The end result is basically capital moving from poor countries to rich countries which have the patents and production capability.
