Months ago, Collider confirmed from J. K. Simmons that there is "one more JJJ appearance in the can" and that "from what I’m [Simmons] hearing there’s a plan for yet another." Since Simmons said that there was already one "in the can," this makes it very likely that his next appearance will be in either Morbius or Venom: Let There Be Carnage.
Sony seems intent on keeping the connection between their spin-off movies and the MCU, an example being The Vulture cameo at the end of the Morbius trailer. This makes it all the more likely for J. K. Simmons to appear in other movies in the future, including ones in the MCU.
In an interview with Collider for the upcoming 4K release of Whiplash, J. K. Simmons reaffirmed his confidence that J. Jonah Jameson will return in more movies.
“There is a distinct chance, there have been discussions, and I’m not going to say anything definitive [laughter] because I don’t know if I’m allowed to. But yes, I’m very optimistic that I’ll have some more J.J.J. in my future.”
WHAT THIS MEANS
There are actually plenty of options for where J. K. Simmons could appear next as the bitter news editor. The most blatantly obvious place that Simmons could appear next is the sequel to Spider-Man: Far From Home, where he first returned to the role. These discussions could still be ongoing due to the many delays that Spider-Man 3 has faced since the pandemic started.
Another possibility could be Wilde's Spider-Woman movie currently in development at Sony with possible involvement from Kevin Feige and Marvel Studios. Including J. K. Simmons in this movie could go a long way in helping cement Spider-Woman as being part of the same universe as Tom Holland's Spider-Man.
Once more possibility is the Kraven the Hunter movie in development at Sony. The directors for Kraven and Spider-Woman were announced around the same time, and including Simmons as a public figure demonizing Spider-Man could spur Kraven into hunting the young hero.
Wherever J. K. Simmons ends up in the future, it'll be interesting to see how he is portrayed moving forward in both Sony's spin-offs and the MCU.