Question to biologists: Is cross contamination an issue? e.g. Monsanto corn has contaminated non-monsanto corn through wind/pollen/whatever natural mechanism.
Is there a non zero probability that sometime in the future I'll buy standard yeast for cooking at the store and get some of the kind described in the article?
No. First of all, this modification brings a significant handicap to the organism (it's wasting its resources), so it can't spread in nature. And even without any competition from wildtype yeast, it's likely to get rid of the opium pathway by itself once enough generations have passed.
Anyways, yeast culture is done in closed environments with specific varieties as stems.
The invasive potential of some Monsanto varieties that you mention arises from the fact that they were modified to be resistant to specific pesticides, giving them a significant advantage since these pesticides are everywhere.
Is there a non zero probability that sometime in the future I'll buy standard yeast for cooking at the store and get some of the kind described in the article?