I think the answer to this question (with emphasis on "all") is clearly none that we know of. Plastic is really hundreds of different polymers, each with different priperties and uses.

If a new material can take the place of some of those, that's a win. We don't need to replace plastic wholesale with a single new thing, there's no rule against using multiple targeted materials, we've just got used to material science being all about one material for recent history.