We will be changing our policy so that only the latest stable build will be officially supported. This is done in an effort to concentrate resouces on building new and great things, instead of wasting a lot of time merging from old versions. A lot of -competing- projects have this policy and thus can move faster. We don’t want to carry that disadvantage any further with us.
For folks with support contracts, of course nothing changes: we always supported all versions – no matter how old – under these contracts (as long as technically possible). Please also note that we always consider older, but frequently used versions when it comes to important bug fixes (for example, I lately added a couple of fixes to v5.10, which is no longer officially supported for quite a while).
I would like to point out that rsyslog has a very considerate version management, with keeping major versions in different branches and (via professional support) taking care of each old version. This enterprise release scheme is under no discussion.
As a side-note: the discussion was started when I thought about non-critical fixes that I did for v7 and we thought about if it really makes sense to spend time to backport them to v6. There are also some enhancement-like "bugfixes" (like better config error messages), which will stay with the devel branch and mature into the next stable (if for nothing else, than for their regression potential).