So, who thinks they're going to make Mirage Arena an online thing?
Personally, I find it more likely that they'll scrap the online idea and just make it a single player world. However, the idea of implementing online multiplayer is a big marketing ploy nowadays, so it may actually serve in their favor to make it online.
At the same time, online multiplayer has become something of a gimmick these days ever since developers thought it was mandatory to have an online mode after it became so popular, and thus people aren't instantly sold on a game if it includes online. So, it could go either way.
I, for sure, would be spazzing out from pure joy if they decide to make Mirage Arena online. There weren't many people playing BbS around when it was first released in where I live, so I never really played co-op with or versus against other players. To be able to experience it in PS3 is an experience I will welcome with arms spread wide.
If, though, it no longer supports multiplayer, then too bad... but I can still cope with it. Going solo through the matches was a very challenging, yet very satisfying, experience that I wouldn't mind reliving. It's just like Olympus Coliseum's Sora-only mode after all, and it's certainly doable and far from boring (unless you keep losing. Sweet Swirlix, that goodness-forsaken Iron Imprisoner IV took me more than 10 tries to beat in Critical).
That said, I'm leaning toward the "yes, online, please" side. I hope they really make it happen, because not doing so is... somewhat a waste of the potential that the Mirage Arena possesses. That's my opinion on this.