Actually there are now two mailing list discussions surrounding the matter. The original thread appears to have been abandoned after several Mesa developers were upset with the tone of Airlie's message and it coming across as rather offensive. As a result, a new thread was started. Brian Paul, the founder of Mesa, has responded with his view on the situation, which is worth reading, whereby he is trying to push the largest number of bug-fixes into stable branches of Mesa.
At the moment there are some possible changes being discussed such as having a stable release maintainer that would be responsible for pulling fixes from master into stable Mesa release series, to devise a release schedule, etc. However, no definitive changes have resulted from this discussion yet.