The problem is the whole aproach to the hardware issue. Since Amiga has decided to create the OS and don't care about hardware, you'll never have a product that you can call "revolutionary" in the sense of the Amiga500 or attract a lot of users to the platform. Basically, the traditional hardware market is already taken by Apple, MS, Linux, Ati and Nvidia.
What is needed is a whole new platform. I know some will say the days of custom hardware are over, and I believed so some time ago as well, but talking to someone who's quite a genious in hardware and low-level coding, I'm becoming conviced that it is possible to create a whole new platform that truly embarasses those companies that now claim to have the ultimate saying when it comes to hardware innovation.
It has to be a whole new concept that is not concerned with issues of backwards compatibility. This is not only at hardware level but also at OS level.
I have no doubt that OS4 will very interesting, but alone it will never have the capacity to be on top.
That of course doesn't mean we can't have a nice community around it (as I hope will be the case), but to rule the world a much larger scale effort would be needed at hardware/os/applications level.