I think the real truth is, and im sure bliz knows this. The people who would really quit if they started selling gold are few and far between. This game is like crack and your addicted. You honestly think with your 5+ years of playing your just going to set it down? Of course not. Video game rehabs didnt start springing up for nothin ya know.
Heck i still think about playing Ultima Online and its been a few years since i kicked that habit.
When I can't buy crafting mats or enchant scrolls in the AH because RMT has inflated the prices to an area I can't touch without buying gold myself? Yeah, I'm done. I've had video game "addictions" before WoW, and I'm sure I'll find another one after.