If they ever do add flying to the old zones, this should be accompanied by merging the shroud, la noscea and thanalan zones into two zones each, instead of many small zones as they are today.

Since they would already need to redesign parts of the zones to accomodate flying, that would be a good opportunity for larger re-designs as well.

If doing that would mean less work going into new zones (4.x I guess is next time we get new zones) however, I can pass on flying in the old zones.