I think TOR has value in the larger narrative of the MMO genre development. It definitely proved that you can provide an awesome story experience without sacrificing the MMO aspect. I don't think the execution was perfect, but the combination of your individual story line with the planet lines with the dungeon lines really worked to give you a whole slew of story content across both solo and group play.
Imo, the next "huge" MMO is really going to have to match that.
Also, I don't think the next "huge" MMO is going to be what WoW was. I think it's going to be a long time before anything is what WoW was. And I don't think that's a problem.
When you look at the last two years or so, a few MMOs pop out. Maybe not because of popularity, but because of ingenuity.
Secret World provided amazing customization potential for players. TERA proved that you can adapt typical MMO gameplay to be active and enjoyable. GW2 has proved that you can make a successful game without sacrificing any of those areas (though I don't think they'll be the exemplar of doing so). GW2 is also likely to set the stage for future F2P RMT systems, imo. It's going to be hard to justify paid content to players when your competitors are limiting RMT transactions to peripheral quality of life systems alone.
Example: TOR is limiting their players by: Restricting F2P to 1 crew skill slot, no cargo hold, very limited inventory space.
In GW2, you have 2 active crafts at a time, and switching them is a very small game currency fee. But your progress is saved in all crafts, so you can take every single one to cap on any character without any hassle at all. You only have 30 bank slots by default, and they are account wide, but you get a MASSIVE amount of raw material storage--every single raw material has a slot in your "collections" tab which will hold up to 250 of them. You can deposit all of these from anywhere in the world by the click of a button. You get your main backpack plus 4 bag slots by default (I feel like 10 slot bags are the largest right now), which actually is plenty of space because you never need to store the crafting mats you are picking up. Plus, you can carry salvage kits around to break down gear drops you don't want, then deposit those directly to your collections tab.
It's not hard to see which one is more generous. By a landslide.
Elder Scrolls Online is already shaping up to learn from those lessons. While I'm disappointed in the game from the point of the view of its IP, I'm liking what I see about the game separate from that. It just isn't an Elder Scrolls game--you won't be gallivanting around the world chasing butterflies and arbitrarily killing whoever the hell you want.
What they are promising, however, is complete customization freedom with regards to weapons and skills. They're promising combat that isn't about watching keybars, but rather more like the ES games now (left click for your main hand, right click for off hand, double click off hand to interrupt, etc.). Allegedly those keybar skills are more like TOR's heroic moment stuff. You won't use them every fight, and they're meant for something big. IIRC, they actually spend a resource you earn independently of combat mechancs (like completely quest objectives or killing enemies), but I can't really remember and it's not important enough for me to go looking.
If they can deliver on a story that's at least within sight of TOR's, then I expect the game will do great (assuming they don't: A. Go for a sub system and B. Go the TOR route of F2P). They could do well with subs, but it's just so much harder, particularly in this economy. When you aren't rolling in dough, It's HARD to rectify spending $150 a year to pay a single video game you already bought for $60. Especially when you have great F2P options available.
So, in this kind of sense, TOR was successful. It proved something about what an MMO can be with regards to story content. If they had been more adventurous with their systems, if they had launched F2P with something in the ballpark of GW2's generosity, if they re-imagined any typical MMO systems (or hell, any one of these things) they would have done way better.
It'll be close, but Romney has the momentum.