Don't forget, among the companies that are sinking money into replacing Android is also Google. They're preparing for a fight.
Times when OS's were fundamentally replaced because of industry paradigm shifts:
- Unix -> Linux
- MS-DOS -> Windows
- Windows 3.x -> Windows NT
- ProDOS -> GUI ProDOSs
- Android with a Blackberry clickwheel interface -> Android with a touchscreen
- Windows CE -> every other mobile platform
- Mac OS -> OS X
- OS/2 -> Windows NT
- CP/M -> MS-DOS
and so on.