Your proposal to have the lender reset a $500,000 mortgage for $300,000 with the lender taking a stake in the future profit of the house makes more sense than getting the government to do the same.
When government gets involved we know they will get political.
The government created the housing financial mess by promoting equity loans and subprime borrower loans.
I roughly calculated that the US housing stock has a value of about $12 trillion. If we can prevent more foreclosures from driving down the market value of all houses, then the US housing stock remains at $12 trillion.
As we all know in a market it only takes a small percent of sales to drive down the price on the entire inventory.
It is not only the US who is trying to prevent a meltdown in housing prices. If housing prices meltdown, it will have a ripple effect into other markets and then we have a global depression.
I’m not advocating it, but I think where gubmint would get involved here is in somehow financing or insuring the initial “forgiveness.”
Anyway, I know I would give up some of my future profits to “buy” a reduced mortgage payment now. There are lots of ways that would help the economy. I see that as a win-win for the economy (and, again, much different from buying the paper off deadbeats).