Jack Black said after Jumanji 2 he'd do KFP4 and that comes out 2019 and that leaves me thinking Panda 4 could come out 2020. I have good feeling it will. Panda 3 released January 2016 and Jack Black was another film before that Goosebumps which was around November 2015. A lot of Google articles are saying 2020 is a safe bet.
However Jack Black said this will be the last one he will do. If Kung Fu Panda 4 is the final one which I hope it is. I hope it's just as good as How To Train Your Dragon: The Hidden World.
Here's my video which I go in a lot of detail: youtu.be/XcnTlOOC1jY