from wx roadmap :
New development happens on 3.1 branch. The latest version is 3.1.3, released on October 28, 2019 and we plan to release one last 3.1.4 release in 3.1.x series in the beginning of 2020 with 3.2.0 follwowing soon afterwards.
One of the big planned changes for this 3.2 is better support for high DPI displays, but there are, of course, many, many other fixes and improvements in it as well.
3.2 will also finally drop support for very old legacy systems (such as Win9x platform) and compilers (MSVC6, maybe MSVC7 as well).