For me, once you unlock Flying at 60, it should never be taken away - not even by Pathfinder bullshit.
But for anything like you or I suggest to happen, Blizzard definitely needs not only to improve mob's air awareness, but also rework Mounts, fall damage and surrounding mechanics.
I made a suggestion once regarding all that, but people were raging so much about wanting flying yesterday that very little constructive feedback was provided.