I'd rather Blizzard didn't bust their balls trying to give WoW a complete overhaul. I'd much rather they funnel a large proportion of my subscription dollars into designing and building something totally new, i.e. their undisclosed "Titan" project.**
I still enjoy Warcraft (especially this new MOP expansion, it's very well done, some of their best work yet), but having played for just over seven years now, it is getting a bit long in the tooth. The game has aged remarkably well, but it's not as if it's going to last forever, that's totally unrealistic.
** Disclaimer: I of course have no idea whether Titan is in fact going to be totally new and awesome. I'm just hoping that it might be. **