Microsoft have recently announced Visual Studio 2013. As part of this announcement it appears that WP7 has now fully been tombstoned - any WP7 project loaded into VS2013 will be converted to WP8 - and you will not be able to deploy it back to a WP7 device.
Further, the brilliant work that Microsoft and Xamarin are doing together for cross-platform Portable Class Library functionality will be based on the VS2013 reference assemblies - and these will not include the older WP7 compatible profiles like 104.
Because of this, I'm sorry to say that MvvmCross will very soon be dropping support for WP7.
In the period of the next 1 to 3 months:
- all MvvmCross Portable Class Libraries will shift to Profile 78
- only WP8 and later will be supported by MvvmCross
I appreciate that many MvvmCross users and many of my customers have been great supporters of WP7, and I also appreciate that 50% of currently active WP phones are 'stuck' on WP7.
However, I'm afraid that it's simply no longer possible to support WP7 given the death of tooling support in PCLs and Visual Studio.
I hope this isn't too big a problem for anyone - I will branch the code so that a WP7 archive exists, but beyond this, we will look forwards to a bright, portable future with WP8 and beyond.