Actually...

exactly which part of Android depends on Linux?

They could move tomorrow to a Windows NT kernel, and no one would be the wiser.

Heck, that's just what http://www.bluestacks.com/ and all the other Windows android implementations do.

Heck, that's what Alien Dalvik does! Even on iOS!

Android uses their own interfaces/HAL layer for almost anything that could be kernel-specific: audio, video, IPC, bluetooth, network, even security. It has as much to do with Linux as MS dotNET. And you can certainly trust Android does not have the best intentions for Linux at heart (rather the opposite), with even the Google ChromeOS guys having contributed more (in lines of code) to the kernel than all the Android guys combined.

I'm still surprised how little people realize that Android went to huge extents in order to abstract themselves from the kernel -- possibly so that if the need came they could move to a BSD/Apache or proprietary kernel. A need that did not come by because no one seems to care about GPL compliance either way.

(Sorry joerg_rw for the offtopic :P )