Nobody wants an XI-HD. Thats not what we're talking about. I just recently said this same thing in another thread...

-Horizontal progression gives lasting value to end-game acquired items.
-Slow leveling gives value to items ranged 1 to Cap, and the level capped content that rewards them.
-Both of these keep you in the game longer.

Vertical progression won't keep people playing. Don't kid yourselves thinking every time the level cap rises you'll feel like its a new game. Everything you spent soooooo long trying to get (2 weeks?) will be useless, and it'll feel like you're starting over. That won't keep anyone in the game for 8 years. Years 1-7 will be wasted time, the only stuff you'll use will be from year 8. No thanks.