One thing I've not yet seen mentioned here, but which has certainly been often mentioned in the past, is to refashion RISC OS.
Linux is moving rapidly and capturing new ground as we speak. Why not implement the most cherished part of RISC OS, its GUI, on top of Linux? Many familiar things would have to change of course, but in light of a new born RISC IX (or whatever). The important thing is that the overall user experience will stay, not the dated technical background that makes it work.
It's a foregone conclusion that the era of ARM based RISC OS machines has ended. Actually, it's not so hard to imagine why the Iyonix was the world's first XScale based desktop computer! Probably it'll also be the world's last ARM based desktop computer.
I don't see the future of our favourite platform inside an ARM emulator, or rather, an Über-RiscPC emulator. In my opinion, there's not enough incentive or room left to allow it to grow and evolve in that state (or rather prison). I think we need to rely on open source based development, which is typically linked to Unix-like platforms, to be able to have a strong future. When the RISC OS GUI is rebuilt to run on top of Linux, we can enjoy the comfort of our favourite GUI, while also being able to reap the full benefits of Linux and Unix development efforts. Current ARM-based applications could run inside an emulator like RPCemu or even a layer that neatly blends into the new RISC IX desktop. Think the Classic environment in older versions of Mac OS X - [link](Mac_OS_X)