You are giving me a head ache again.
Really? Nothing to gain? Nothing at all?
I guess the prospect of a common underlying OS offers nothing.
No benefits from having a common set of kernel, libraries, apis, etc.
Windows CE has historically been good for embedded devices... only developing (for) it (app or OS level) generally required two different, rather different code bases.
Yes... there will always be differences between platforms (embedded vs desktop, server vs client, mobile vs web, etc)... the more commonalities you can have, the far easier the end to end development story is.