I think building a tier 1 (or even tier 2) from scratch has gotten a well deserved reputation for being borderline impossible. Just consider how many great eff

I think building a tier 1 (or even tier 2) from scratch has gotten a well deserved reputation for being borderline impossible. Just consider how many great efforts have crashed in the last 20 years: AmigaOS, GemOS (Atari), OS/2, BeOS, MacOS9, Palm, Symbian, WinCE and others. The ones that are still hanging on don't paint a much brighter picture. I'm sure there are a few teams out there that would have a good shot, but the daunting task+access to good/free that your staff already has experience with... well. That said, it's great MS is still at it - heterogenous infrastructure is probably a lot more resistant at a macro scale.