For me the hottest candidates to sign Dembele are definitely Chelsea or PSG. I don't think that Bayern is really interested in signing him as they have just made the transfer of Sadio Mane which is also a winger and now they have Mane, Sane, Gnabry and Coman which are basically 4 world class offensive wingers so i highly doubt that they want to have a fifth one because only two of them will play most of the time.
A move to Chelsea would make sense because Dembele already played under Tuchel during their time at Borussia Dortmund and Tuchel is still a fan of him. Also PSG would also make sense because Dembele is french obviously.
I also think that the chances are low that Dembele will be goes to Bayern Munich , but on the other hand if Gnabry make the decision to leave the Club it would be an option.
Bayern Munich looking more for an player in the defense and an possible replace for Lewandoski if he leaves.
I think Barcelona and the player would eventually find a common ground, things seemed to have settled way better than it was between both parties some month back and since there aren't too many club willing to take the risk with him, he might need to prove himself a bit more at Barcelona, and given that he's still just 25, provided he can stay fit for the long term, he's still got a whole career ahead of him.
The problem with Barca is that the future is not clear with the financial problems they have.
I guess Dembele has better chances and future on a another Club and after he can leave the Club free we i think he is playing somewhere else next season..