What happens to modern society when bacteria, fungus, and other assorted critters evolve the ability to break down plastics?

Probably something similar to what would happen if bacteria, mold, insects, et. al. suddenly started being able to eat wood!! Look around at all the things that are made of wood or use wood in their construction. Civilization would surely fall if that were to ever happen. Maybe if we're really lucky it will never happen. Or maybe, just maybe, we'd learn to deal with it.