For sure. I've seen complete trading systems written in Excel macros.

MS have played their hand very astutely and have managed to capture a large fraction of the enormous gap between cost-to-producer and value-to-user. Keeping things that way is worth $100bn market cap to them, and challenging them is worth relative peanuts to anyone else. Of course they're going to win every time.

Our best hope is that someone like Google pours money into a fully-compatible fully-featured desktop replacement out of sheer spite.