Doubt he's coming back. He's very angry with Disney at this point, and they haven't given any indication they regret burning bridges with him either. Disney seem to be working on a semi reboot/sequel now without Depp, and i'm guessing it won't go well for them.
I doubt we're getting any more Beasts movies either. The second one heavily underperformed at the box office and the third one is considered an outright flop. WB said they were waiting to see how the third one would do before greenlighting more, and we can surmise they didn't take to the news well. The third movie even feels like it was made with the assumption that it might be the end of the series. One very minor change to the ending scene and you could easily call the plot wrapped up and finished.
I was disappointed that they recast Grindelwald. I thought FB2 was a fairly poor movie, but Depp's performance was excellent and one of the few legitimately great things about it. It's a shame he wasn't kept on for the third, I will always associate the character with Depp. The only issue I had was his look. His reveal in FB1 actually made me skeptical i'd enjoy him in the role. But he ended up doing a great job. Not a good movie, but he singlehandedly made it worth sitting through. I still wish they had kept his long haired look from the beginning of 2 though.
FB3 was a FAR better movie than 2, but Depp's absence negatively impacted it IMO. I think Mads is a highly capable actor, and he made an excellent Hannibal Lecter. But his performance as Grindelwald just wasn't nearly as good as Depp's. It was merely ok. Not a bad performance, just a lesser one than what I know he's capable of as well as what Depp pulled off.
