No, it's not the future, and neither are touchscreens (in a desktop environment) or glass keyboards. Just because something looks futuristic, doesn't mean it's practical. In the case of Natal, it suffers from the same thing that touchscreens suffer from in a desktop environment: gorilla arm. Natal's gesture based control is only useful for brief periods. If you had to keep your hand flapping around in the air for a couple hours, you'd be damn sore.
That and the sort of control that Natal can provide is completely lost in a desktop environment. The desktop is predominantly overlapping 2D windows with control buttons. An optimal control scheme for that environment is something that is precise and operates on a (surprise) 2D plane. Natal is inherently a 3D control scheme. Our entire OS interface would have to be redesigned from the ground up to really make use of it. Unfortunately once you have redesigned the OS to integrate well with a Natal-like control scheme, you'll have made it highly inconvenient to use by traditional 2D input devices. Thus you're then stuck waving your hand around in the air all day long.
If anything will could effectively replace the mouse for general purpose work, it'd be a large mousepad sized trackpad with advanced gesture recognition. Even that has its drawbacks though, both ergonomically and functionally.