First of all, anything that is reasonably dry usually stays reasonably safe against bacteria. Unless the bacteria learns to combine oxygen with the hydrogen from the hydrocarbons to form their source of humidity, I think these should be relatively stable, still.

And we still have the option to store things in metal containers, like cans if we need that extra durability.

But under humid conditions, if bacteria become able to consume plastic the way they can consume organic matter, I would be even more concerned about regular grocery wrapping. Not only could the wrapping break, one could also get half-digested toxic materials into the food itself.