Anyway, I voted for Fusion. :)
I heard Fusion is for the use of a Wintablet as a controller like device for the new Xbox (with the Wii-U doing so awesomely I suspect it will be supported in 3-4 games max), and some devs have suggested some of the SDK has options for this.. The early ad markups have the infinity symbol.. so I will go with that.
Xbox 720 is a possibility but probably a slim one. I guess you can drop the Xbox name and go with 360 and a superscript 2.
Someone on Google+ (one of the places where I cross post the blogs here) suggested Xbox with a superscript 2, i.e., Xbox Squared. I doubt they'd do a superscript 2, plus you can't call it a 2 when the competition has a 4. That's why it was never going to be Xbox 2, since Sony was going to have the PS3. A superscript infinity symbol is far more likely. You also have to have some flexibility for the future, which is why the Wii was never going to be called Revolution, even though everyone seemed to like that name. That's why I think "Fusion" is probably safer than "Infinity," though of course at that point you probably could do Infinity Squared for the next console after that. Marketing. Ugh.
I added two new options, "Xbox" and "The Xbox." Apple-like there.