As a subscription based game, raiding is a lot more important than you give it credit for. SWTOR and GW2 are both great games before you hit level cap. But SWTOR and GW2 lost a lot of customers when people reached level cap and main reason is "there is not enough to do". WoW's end game (raiding) is what keeps WoW rolling.
Granted, raiding isn't the only thing (and it doesn't have to be), but it is the main draw of WoW for peple to stay. I can tell you without raiding, there will not be a subscription based wow. Blizzard has been playing with other ideas to keep people playing and let's see some of these ideas:
1. pet battle
2. dailies
3. pet/mount/title farming
Other than these, players simply consume contents faster than what Blizzard can put out. And I don't think any of those can keep players paying 15 a month. Another choice is to put out new compelling content very rapidly so players feel each patch is new and fresh and stay subbed. This is possible but I think this model is much harder to maintain compared to the raiding model.
MMO genre as a whole, no company has been able to come up with another end game activity to keep players paying 15 a month so raiding is here to stay. I think eve online has some pretty cool crafting system so players mostly pvp + making things for end game. But again, eve online is no where close to the scale of WoW. If WoW does go F2P then it's very possible that WoW would stop producing raids (or change payment model so you pay to have access to raiding).