What I truly think about the whole idea is Google would be the winner over Microsoft, eventually!
This movement and this step taken by Microsoft would bring a lot of damage to Windows Phone Operating System. People wanted to enjoy the experience of windows phone. That's why me - myself - bought a Lumia Phone.. Any chance of ruining this experience will drag MS to hell, I mean it.
If I went along with MS just because of the clean UI Microsoft represent and suddenly Microsoft decided to bring other apps from another OS whatever this OS is.. The whole experience will take-off.
The bottom line is:
WE WANT WP BECAUSE WE LOVE ITS NATIVE APPS THANKS TO WP UI.