Then you'd get a stable, modern, secure kernel with all the features RISC OS's kernel lacks. You'd inherit all sorts of advanced tools from the unix world, including debuggers far better than !DDT, and ports of FireFox would be far easier.
It's along the lines of what Apple did with MacOS, and it's transformed the OS to a leading-edge design.
Or, at the very least, someone should make (most) modules run in user mode.