Once you're done with the weeks raiding in WoW (2-4 hours roughly), what is there to do? Crafting and PvP, I'm not going to add Rep farming into the mix as that is now incorporated into the levelling process . That's no different to what's on offer in GW2, the only difference at the moment is that blizzard have 8 years worth of fine tuning and experience to fall back on so they have the time sink element down to a T.
GW2's 'end game' for want of a better word is Orr for those that PvE. I think that ANet need to look at how quickly people have been blitzing through and downing Zhaitan and make it harder, more of a time sink so to speak. The usual MMO end game is all about a time sink treadmill designed to keep those people that enjoy that experience playing, more commonly called raiding. As we don't have raiding in GW2 (yay!) Anet need to apply those same little hooks into Orr imo.
I honestly feel that the devs will get the balance right, maybe not with Orr and this elder dragon but the next one certainly.
The above is personal opinion I haven't gone into Orr yet, as I'm only a lowly level 30 on my main and 27 on my alt (finally decided on class, woot)