Or incorporate it. Basically what George Carlin said. Evolution will witness a new paradigm of life plus plastic and will keep evolving as if nothing matters.

Maybe?

Evolution takes a long time and unless we are dealing with microbes and fungi, generations are counted in years or decades.

I think chances are higher we all die, the microplastics get embedded in a layer of rock worldwide, and nature moves on without us. Evolution is way too slow to keep up with manmade horrors.

Is 60 million years not too long?

I wholly expect that some time from now humans will gather to talk about the moral implications of letting creatures that depend on microplastics go extinct due to our efforts to remove plastics from the environment or if we should be producing plastics to keep them alive.

...only a few million years

David Cronenberg’s Crimes of the Future takes a look at the idea

...or go extinct.