I think it will be more than 1...20lbsThen everyone would drop one weight class
If this is some sort of attempt at reducing weight cut that is not the answer, the answer is more weight classes, 7lbs apart going from 125lbs and up, no more huge weight cuts, even tho, some will still try to do it, but most will fall into a weight class not that far from their ideal weigh-in weight and probably be able to fight in more than one weight class, it would lead to more belts tho.
They'll never stop cutting weight. They'l never stop almost killing themselves to have ANY advantage possible.