Natal will flop.
To do what it's advertising, it will have to have some raw processing power all of it's own, which means it will be an expensive add on.
Not to mention the supposed dashboard integration.
Already NXE is pushing system resources and is not very responsive.
As for adding it into any popular games, not likely.
I haven't looked at any of it's stuff lately, but it appeared to be a gimmick that may not even see production.
Give it 2-3 years and the next gen consoles will be in production. Maybe then it'll be worth while, or do what NXE did and give us a Wii clone...and by that I mean shove a Wii avatar down our throats.