Werner was bought to score goals. I'm sure the board still expects that of him and I'm sure he still expects that of himself, but what is becoming clear is that he can't be relied on as the team's primary goal source. The way things are unfolding, the more it looks like he'll be similar to what Pedro (or maybe even someone like Anelka) was to us, someone who will score goals - and provide assists - here and there, someone who can be the secondary goal source with like 10-15 goals per season, someone who can be the supporting act to the main striker.
As for his problems, I really want to know if anything happened behind closed doors in the last INT break. Even though he was still missing some chances back then, every thing started going downhill for him after the November games, when it also included Germany getting spanked 6-0 by Spain.
Apart from the swap deal talk, I don't see why we should bin Werner after just one season. If we're still talking about the same issues this time next season (hopefully not), then sure, we can look at that. Giroud looks likely to leave this summer. If Abraham doesn't want to sign a new contract, then we would be looking at another sale there. Potentially letting 3 strikers go at one stage would be crazy.
Moreover, if we want to challenge Man City and even Liverpool for top honors, then we're gonna need a good squad depth. Plus, it's worth remembering that while Pulisic is fit right now, he still has that dodgy injury record hanging over his head and Ziyech will be gone for at least one month in January next season.