Possible. I think the optics do look bad now. However, IMO, the post-cup win on-ice interviews from McLellan and Trotz led me to believe that his odds of returning were not good.
Huge piece of their puzzle? That's debatable. If Trotz was what you say he is, then 2015 and the 3-1 lead they had against NYR should've resulted in something more substantial.
That'd likely require a horrible 2018-19 from the Caps, coupled with a superlative 2018-19 from whichever team hires Trotz.
Not sure if Trotz's resume prior to this season was all that great. He'd never made it past round 2 ever, but he is a cup-winning coach now and that's what matters for the moment. As to what message it sends- that is debatable. Washington kind of painted itself in a corner in the way it dealt with Reirden and Maclellan's statement about this last season likely being WSH's last year in the contention window (or something to that nature). Mac/WSH made his bed and they have to now lie in it and hope for the best.