Interesting theory, it actually makes good sense to some point. Maybe its just that simple, to use kyuubi's chakra to sustain attacks like the rasen-shuriken. iirc, tsunade said that naruto's cells that carry the chakra could be sliced/cut wen he uses it, so maybe w/kyuubi's chakra he will eliminate such risks.

Or it just be completely something else. I guess only time will tell. Good theory tho =]