I have long been a proponent of something like this (http://www.slate.com/blogs/moneybox/2012/07/25/jeff_merkley_s_plan_for_underwater_homeowners.html). While I have not been following the housing market that closely, my one hesitation is that the time for this may have passed. The bubble began bursting almost five years ago.
What we want to happen is people stay in their homes, continue to pay something. Empty homes benefit no one, due to the lack of maintenance vacant homes can have serious spill over cost to neighbors as well. The difficulty is how to price the sale from the mortgage holder to the government in such a way that neither the banks nor the American people get screwed over (though the first one is negotiable). I am not sure a method could be worked out.