With an estimate of upwards of 400,000,000 guns in the hands of civilians here in the U.S., those "thousands" handed over in government street pawn shops will only help gun people fund purchases of upgrades.
I'll call it a win for the citizenry.
No doubt they will be destroyed. If only the ones not found to be stolen, would be sold to law abiding citizens, through an ffl, to raise funding for......community programs!