Probably best explaining of the new situation and everything what happened before and after decision of phpBB team come from opinion of one of the oldest and probably best php coders which mods official are never verified from phpBB team - Ptirhiik (creator of category hierarchy and their integrating into phpBB):
From http://www.phpbbhacks.com/forums/phpbb-2-s...09-vt72608.html
With main point:
who will trust the phpBB team in the future, knowing they announce they will keep security fixes even on old previous version (that is what they have claimed since the release of phpBB 3, and before), and finally drop it in such a short time line ? I won't for sure.