IMO Acorn went down because they effectively stopped developing their own unique hardware-technology after the RiscPC was released. By the time they noticed this mistake and restarted development of their chipset for the Phoebe, it was too late. They also did not use the little influence they had on ARM properly. The ARM3 had multi processor capabilities. Why was this dumped?
IMHO if you want a brigt future for RISC OS, you need to support the companies, wich develop both the OS- and the hardware-technology. We need our own chipset, because otherwise we will always be dependant on low-end chipsets for the embedded markets. Of course any company doing such a development has a lot of catching-up to do. MD for example first had to duplicate the efforts Acorn did betweeen the first Axx machines and the Phoebe. Now that this has been done, they will continue development to catch up with the rest of the industry, starting with features like FPAs (floating point accelerators), graphics acceleration (tailored to the WIMP), etc, wich can be implemented in the Omega and then speeding these up with the newer FPGAs from Xilinx (already available) in new machines, when the Omega's FPGAs have been used to their full potential.