Listen, I'm calling it now. If they put a 50 year mortgage in play then within a year they'll be selling 0-down subprime mortgages with an attractive 5-7% teaser rate and a variable APR that kicks in if one, maybe two payments are missed.
Imagine the mega-tsunami of foreclosures that will result once that APR kicks in and your 50 year mortgage goes up to 27-35% interest compounding monthly. No one can take that.
Once they get that going they'll start bundling these things into some new security... Long-term mortgage equity securities or some such. And it will be '08 all over again in the housing, banking, insurance, etc. markets.
When the crash hits, the same banks that traded the securities will buy up the bad debt, and thus the properties attached to it, from each other. They'll call it clearing the bad weight or something.
But, in fact, it will be probably the final instance of wealth and property transfer from the many to the few.
And the system will go into free fall implosion.