Pretty much this. A Blizzard developer said himself that you will never beat WoW if you just make another clone of WoW.
Actually, Extra Credits from Penny Arcade put a really good perspective into WoW clones.
http://penny-arcade.com/patv/episode/the-future-of-mmos
All I think can be said in the video above. The only games I see succeeding and staying in competition with WoW (not over succeeding it) is Final Fantasy XIV 2.0 and Guild Wars 2. FFXIV 2.0 will definitely caters to a certain group of people (Japanese and JRPG players), and the idea of international servers is one of the reasons that FFXI was a huge success for a long time.
I played SW:TOR and got a Bounty Hunter to 50. I will say beforehand, the story was incredible and it was better than all the three prequels put together. However, that is as far as I can say about it. It not only pretty much used WoW's form of end game style, it also was no where near casual friendly. I remember in end game, I had to do dailies on two planets that had group oriented quests and easily took me 2-3 hours to take care of all of them (assuming you have a party ready to go), not only that, a daily was required of you to finish a dungeon. I don't know if you played dungeons in SW, but they were not short by any means. You were looking at a good two hours to finish a dungeon. So if you wanted to be as progressive as possible in the PvE department, you had to easily sink 5-6 hours of gameplay a day.
Like someone said, WoW caught lightning in a bottle. They found the balance of casual play and hardcore play. Making it so you can gather your Valor Points anytime of the week, you just had a weekly cap instead of the old way of getting 120 a day if you were on everyday. It catered to casuals because instead of feeling forced to be on everyday, you could get whatever you wanted done on the weekend and still make the same progress as a hardcore. Of course, ultimately hardcores succeeded over casuals with hard mode raids.
The concept should always be this way, making a balance between hardcore and casual but ultimately rewarded the hardcore more in the end. Hopefully FFXIV 2.0 and Guild Wars 2 sees this and make sure that balance is set in their game.
I believe FFXIV 2.0 and Guild Wars 2 will be highly successful because they don't clone WoW, simply put.
FFXIV 2.0 at worst will derive concepts mostly from FFXI and use concepts that made WoW successful without cloning it (Like a content finder system, this should be a standard tool in all MMO's.). That is okay though, since I believe FFXIV shouldn't be exactly like FFXI, but it should give us a sense of familiarity. If I am a FFXI vet and getting into FFXIV for the first time, it is good that I have some sense of familiarity to get me hooked in. At the same time, a person who has never played a FF MMO should be comfortable getting into it right away. Looking at everything so far and by interviews, it sounds like this is exactly what SE is doing. So I believe FFXIV 2.0 will be a major success that SW could not.
Guild Wars 2 will most likely succeed because it's main intent is to break away from the generic MMO formula, and by playing the beta, it really shows, and in a good way. Can't wait to play the full retail.