I don't see them breaking RAF for the new zones.
Or preventing race changes, etc.
Or preventing heirlooms.

Way back they posted, if you use heirlooms to level the new races, you won't get realm first even if you're the first to finish leveling.
I'd imagine it will be the same for RAF, race changes etc.

I will level my toons as quickly as I can, provided the game is still enjoyable doing it.
I might level a group of Worgen, but don't have much interest in Goblins.
I won't be in contention for realm first, for anything, but still find challenging myself to a personal best to be quite fun.