First time I've seen a non-Android system run Android apps was on RIM's PlayBook.
But that was more like a (crappy) proof of concept. Win95-type experience.
Tizen is suppose to be Android-ready. Rumors were Ubuntu/Firefox may "be compatible"...
It shouldn't really be too hard to do this nowadays.
The price of horsepower is cheap even on smartphones.
So, running some translation between systems should be possible.
Battery life will be penalized but unless you are Apple - it should be workable.
The question is - will Microsoft go for it. I believe it's a gamble they can't win.
Unless they've decided to ditch Windows Phone OS altogether, that is...