There is no way that the Rams brain trust has already decided a) they don't want him next year, b) can't sign him, c) are going to ignore him this year because they know he won't be with the team. If that was the case, you'd see Thomas and Reynolds playing and Watkins sitting. If you believe that, then a whole bunch of guys with expiring contracts are going to be ignored.
I don't know exactly why Watkins isn't getting more looks. McVay speaks about the context of the play itself dictates where the ball will go. Clearly on some of the throws that have gone Watkins way, Goff and Watkins are not in sync. And I think that's the main issue.
In Watkins former gig, Buffalo, their QB isn't a true NFL QB; he's a runner who can throw the ball. So Watkins made hay by more or less working himself open while the QB danced around and bought time. With McVay it's all timing, route running, and progressions. That's how it is with a pocket passer. And it's new for Watkins (he can't freelance).
I have a hunch that some serious time was spent during the bye with McVay, Lefluer, Watkins and Goff trying to figure it out and how to get on the same page.
Snead didn't give up a solid CB and a 2nd rounder to rent Watkins, and then under utilize him, for one season. Watkins was (is?) 24 years old at the time of the trade, and is absolutely a #1 WR with the mentality and the physical ability and has a good resume.....other than for injuries. No way Watkins has been written off or Snead would have been working the wires hard trying to trade him for whatever he could get. No hint of that happening.