They actually do have the right to do this and a technical implementation. Essentially they've escrowed enough cash to run the drm for many years in the future even if they went out of business so they keep their agreements and their customers happy.

Also, having worked in game sales, it turns out that buying "drm free unlocks of long tail" games is not expensive. How do you think things like PS Plus Free Games works? Essentially game devs book revenue now for possibl future revenue lost. It's a smart trade for most games unless that game is say skyrim.