While I think it's clear that some of the currently Oyster-only features could be migrated (e.g., you can have a rail discount card on an Oyster card, but clearly it merely requires a way to link an Oyster card to the "account" of the contactless card), others are more challenging, like free travel passes.

I suppose you could just issue EMV-compatible cards where you grant the holder free travel, though I'd expect this would be more complicated than the status-quo (both in terms of needing to register IDs in lists that aren't particularly long currently, and in terms of needing a much larger standard implemented).