You will be able to download the latest version 3.6 from then on as an archived version, and basic support will still be given on its use or problems that may not be related to the implementation of new features or bugfixes. Sorry to say for all the people still using it, but there are some important, pressing matters that made me decide against further support:
- Functionality: More and more web sites are adopting techniques and code that no longer works in gecko 1.9.2, or cause severe performance issues. This includes large and popular social media sites, blog sites, art sites and most other actively developed web sites on the 'net.
- Maturation of the Next Generation code: The Firefox code base has improved significantly in the last few versions and the initial memory problems are all but mitigated. This means that there are ever fewer reasons to keep running 3.6.x, even on lower-end systems. Pale Moon 12.2 performs well in virtual machines, for example (this has been extensively tested).
- Security: New security patches for problems that also affect gecko 1.9.2 are becoming increasingly difficult to back-port, especially issues related to javascript. There are currently no critical vulnerabilities in Pale Moon 3.6.x, though, so this is a little less of a concern. What is more important, however, are add-ons and toolbars that will no longer be updated and have not been updated for a while already. Each unmaintained add-on or toolbar poses a potential risk. Running 3.6.x prevents you from using updated extensions as they are no longer maintained or developed for that version of the browser.
EDIT: Pale Moon 3.6.32 will be the final version of the Legacy branch, since there are no pressing issues requiring a new version.
It will be moved to the Archived versions and available from there, once version 15 of Pale Moon has been released.