@matthey
I don't think anyone actually believes OS4 (or any other Amiga-like operating system) will directly compete with Windows. In truth, they're not even viable Windows replacements for enthusiasts.
It is true, however, that the days of hardware differentiation are over. There's nothing about the SAM440, Efika, AmigaOne, Pegasos, et al that sets them apart from any other platform, PowerPC or otherwise. It's just a frustrating attempt at continuing the marketing practices of yesteryear.
Whether or not OS4 would be successful on x86 is arguable, but it would at least guarantee deliverability to 100% of the Amiga userbase. I'm sure someone, somewhere has run the numbers. That could explain why Amiga, Inc. put what resources they had behind Amiga Anywhere and outsourcing, i.e. there's no money in OS4 as a general purpose operating environment.