If the support for Natal is built into the engine (as it sounds it will be), then using those tools becomes a much less costly investment in time/development. That being said, I'm down with you not hating on natal, just stating that I think the greater investment for Epic is up front, in the engine, and the dividends (natal support built in for anyone who uses there engine) would defray that cost.
Well said. I can find nothing wrong in what you just stated.
This is obviously depending on natal being a success...as I am pretty sure it will be.