Having suffered through MonoDevelop and now Xamarin Studio (which is much nicer) and the various bugs introduced each time you upgrade Xamarin.Mac and other miscellaneous problems I'd love for Microsoft to come in and:
* Polish Xamarin's tools
* Polish Xamarin's code (and swap out Xamarin's implementation of the core CLR/BCL with Microsoft's own ... presumably MS' GC is two cuts above the Mono one)
* Add more QA to the release process (I don't know how Xamarin.Mac 1.4 got released with a broken NSApplication.BeginSheet implementation)
* Make Xamarin's Visual Studio integration free
* None of those "WCF is Xamarin Enterprise only" licensing restrictions
* Buy MvvmCross too
(Don't get me wrong, Xamarin's platform and what they do is amazing. But even if it works 99% of the time that's still a lot of things going wrong, given the size of .NET. Microsoft's tools and code aren't perfect either but I find I have way less issues with them relative to Xamarin.)