I tend to agree and the article clearly states that eating plastics is still undesirable and the krill's ability to do so deteriorates over time. The article also mentions digestion, but it seems to me, this relates more to the mechanical action of breaking the plastic down as opposed to the extraction of nutrients.
"A world-first study by Australian researchers has found that krill can digest certain forms of microplastic into smaller – but no less pervasive – fragments."
Perhaps they will learn not to ingest it, if it is a problem.?
As for evolution... both speciation and extinction. Extinction doesn't have to happen over night.. it could be over tens of thousands of years or... just fifty.
I still believe that plastics will be consumed by microbes in the future, if not already.
