Tryndamere stated they intend to branch out into other games, creating an MMORPG around their already fairly well established world seems like it would be a no-brainer.
Question is, would anyone really play it over the competition?
Would they adopt a free to play model (likely with optional "premium" service), or would they get saucy and try their hand at a full-featured subscription model (which could work, due to the existing fanbase)?
Makes one think. I'd probably give it a go if they went with free to play, there's a lot of potential in this world they've built.