If you want to get into the heart of MMO failures, it has little to do with consoles. MMORPGs are a dying breed in themselves. WoW was, and still is, the gold standard that everyone else tries to reach. The problem lies in that to develop a game of that quality for it's time, in the time we live in now, requires HUGE amounts of resources and time that we're starting to hit that peak that what you invest into making a top notch MMO isn't going to be reflected in the returns. That's the bottom line of it. They fail financially because they can't get the returns on something they expected to the next WoW. Happens A LOT in gaming, but MMOs like these seem to be the ones going down the hardest. SWToR had huge initial sales, but memberships quickly plummeted because of basic style problems...
I will say this about ESO. It's combat system is not like WoW or SWToR, which imo is what SWToR back. It was a brand new shiny game, using a combat system and overall game style that was past it's time. It had some nice innovations, but it wasn't enough. Still, a few years later the game is still doing OK.
That isn't going to be it. The game has to be attractive over a long period of time to be successful. To do that, you need to set yourself apart from the rest of the MMO's in a way that is appealling. I think the combat system could be that. They are already completely seperating the megaservers for the platforms (well, Mac and PC will be the same). I just hope on that front that they update the PC version frequently like most MMOs do and not let it be slowed down by the console updates. Just throw out multiple patches for the PC version and then lump them all together for the consoles if you need to space those console updates apart and make them huge. They did it for the PS3 and Skyrim...