GPM didn't get shut down, it got switched over to YTM. If you want to use that as an example for what might happen to YTTV, then it'd be YTTV getting moved over to an inferior rebrand that occupies the same space. And I don't know what you're talking about with Play Movies and TV. It's still there.
Google Play Movies and TV was shutdown earlier this year to be replaced (sort of) with YouTube TV -- the same "YouTube TV" in the article above.
https://twitter.com/liliputingnews/status/138170402082645197...
https://www.androidauthority.com/google-play-movies-shutdown...
The shutdown of Google Play Movies and TV and the stuffing of parts of that system into "YouTube TV", is sort of the original catalyst for how Roku and YouTube TV got into this fight in the first place.