Honestly, we don't need another smartphone that can run Android applications. We need a smartphone that runs universal applications, those designed for not only the desktop but mobile as well. Applications that scale properly and give the end-user an experience not found anywhere else.
So I can run Android applications on my Windows Phone. Neat. If I was an application developer, I would be freaking out right now that my programs were being installed on hardware it wasn't meant to be run on. As an end-user, what benefit does this truly offer? The Android applications don't plug into the OS and you couldn't set anything as a default to get a seamless transition from one program to another. You have different design philosophies and dependencies as well.
Just because you "can" doesn't mean you "should".
The Microsoft ecosystem has to thrive if you expect Windows Phone to sustain itself. Piggybacking Android apps is similar in vein to what Blackberry has done with their BB OS and now there is a full-on Android OS device being launched much to the delight of physical keyboard enthusiasts that are permanently placed into the Crackberry praying position. I'm not saying there would be an Android based Lumia device with PureView.