First I think that what Amiga did was similar but not the same. Be wanted to produce their own OS Amiga has the potential to run on all PDA OSes.
Secondly because one company fails in a certain segment does not mean that others have to fail also. A lot of linux companies are gone now but Red Hat is still going strong. But I agree that the embedded OS is tough world to live in but then a PC OS is even tougher.
Thirdly I don't have a PDA or cell phone so I really don't care that much.
