Star Wars: The Old Republic is probably the biggest example.

Edit: Rift is probably another good example, though less high-profile than SWTOR.

Lord of the Rings Online, Archeage, Tera, Wildstar, Kingdoms of Analur, City of Heroes, The Matrix Online are all from that era of every MMO trying to be the WoW killer and needing to supplant WoW for their business model to work.

What's funny is WoW has declined so much but is still clearly a viable business, but I'm sure things like LOTRO, City of Heroes and Tera peaked at higher levels than current WoW. But the WoW of their time was on like 10-12million subs so that was a failure.

Yeah, it's been so long since I thought about some of these that I honestly was blanking on many of them.