Here I describe what could happen if embedded UML takes off. UML inside Apache would become a required feature for all platforms which run Apache. This would be even more true if UML is embedded in other things.
So, the vendors who control those platforms would themselves port UML if necessary, resulting in UML running on all major platforms (including both architectures and OSes).
This would make Linux a universal development and execution environment, and would possible make Linux the default development and execution environment for anyone doing cross-platform development. They could write for Linux and run their applications inside UML on other OSes.