I may return to wow after a few exapansions have been released, when the game is drastically different. I quit for 4.5 yrs and returned and loved it again.
You asked a different player, but thought I'd add that I've moved to Aion. It's free, and improves on many things that wow has to offer. Balance leaves some things to be desired, but it's a much younger game and that will improve over time. I feel like I did exploring WOW for the first time in Vanilla. Character customization and graphics are better, professions and gearing more detailed/complex, quest writing more interesting, characters grow wings, etc. I'm not at max level but have heard that there is more of a PVP focus in endgame (also pvp while flying), but there are also dungeons and raids. It's a little more grindy than wow is now, but the grinds are more interesting (closer to vanilla wow).
When I can afford it I'm trying Guild wars
---------- Post added 2012-12-14 at 11:03 AM ----------
I would definitely play if it was F2P. It's old enough that it may be time for this.
In order to make money, offer better transmog and vanity items items, xp boosts, etc like League of Legends. Perhaps offer 1-2 new BGs/dungeons/scenarios as long as the changes don't affect balance. Landscape skins (e.g., concrete instead of grass), extra dances/emotes, and mini games (such as a side-scroller mini wow) would be fun.