Yes. There's no schedule yet for removal of the GNU Make based system. It remain the default build system for IDF v3.x, and we plan to make CMake the default for IDF v4.0. However GNU Make will also be supported for v4.x.chrismerck wrote: So, hopefully there will be a period of time where we can still use the latest ESP-IDF updates without forcing us to move to cmake. And, hopefully you will have all of the bugs worked out of the cmake system before dropping support for the pure GNU make system. That way we never have a period where we cannot easily pull in updates via git fetch.
So the earliest we could decide to remove GNU Make support would be IDF v5.0 (as yet unscheduled, but definitely not this year). If we decide this then it will be based on the maturity of CMake support, and we will give plenty of notice.
(Regarding the general question of support - releasing of bug fixes, etc - for older major releases, we're in the process of coming up with a more formal policy about this which we will release ASAP.)