They have a back up plan if Bukkit decides it can't update for a long time.
I took this from November's Update:
However, we are devising a backup plan ~ Which means we are looking into creating a super converter, the converter will change all old data to the new data. This comes with a price! ~ lots and lots of time and devotion which could be spent on ensuring a safer and more reliable release on 1.7.2. Again, this is not ideal and would only be created in the worst possible scenario in which Bukkit don't feel they can update for a long, long time.