He could pop up in Strange 2. Presume they both live in NY, who knows.
I'd still love another solo Hulk movie. Looking at what Marvel has in the next few years, when the hell would he even make another appearance?
A thor 4 cameo/minor appearance makes the most sense out of all them. More so than randomly popping into strange. He already has ties to the thor franchise now thanks to taika and the success of Ragnarok. After that success and ruffalo loving the experience, I could see taika wanting to bring him back. He knows valkryie already and it can be something as simple as getting him back to new asgard for shenanigans