With the creation of branch 5.2 done yesterday, the master branch is from now on open for adding new features, to be part of future release series v5.3.x.
Based on the workflow used during the past years, the next future release v5.3.0 should be out after another 8-10 months of development, plus 1-2 months of testing, so sometime in the summer or autumn of 2019.
Even now there is a new pull request on its way to be merged in master branch that is adding a new module – the rtp_media_server:
So the new development cycle is starting very promising. Expect plenty of enhancements and new feature during the development of v5.3 series.
Thanks for flying Kamailio!