Media companies would rejoice. Since such a coordinated move from Google, Microsoft and Apple would destroy streaming for everyone indiscriminately, it would re-level the playing field and enable everyone to start competing anew. Disney, HBO and others would fork Chromium and add DRM support back, then market the shit out of it. They'd start signing deals with phone and TV manufacturers to get their DRM back, each preferably in a way that excludes the others. There'd be a lot of churn as whole media space gets re-balkanized, but that's all good, since churn means they make money.

A lot of smaller companies would die, and a lot of users would suffer - but none of the parties involved actually cares about the users; we're just a natural resource to be stripmined.