It has not been officially confirmed yet but apparently Cavill was being courted by Warner Bros. to make a cameo in the upcoming Shazam! Movie. However with Cavill reportedly being done with the role, it seems that we can scratch out all other future Superman cameos, at least in the upcoming DC movies.
It also seems that Warner’s focus is now on developing a Supergirl movie in which it would focus on her origin story. Because of that, Cavill would also not be able to play as Superman as in the story, he would still be an infant (Supergirl arrives on Earth older than her cousin). That being said, Cavill’s exit is an interesting one as it seems that he might not be alone.
Prior to this report, there have been multiple rumors suggesting that Ben Affleck might also be done with his role as Batman. Assuming that is the case, it seems that if you were hoping for a Justice League sequel, that might be difficult with two of its stars gone.