The formula does not matter. The USPS is part of the federal government. There are no assets to pay for federal retiree benefits for postal retirees or any other federal retirees. The only options to pay for retirement benefits are taxes, fees, and printed money. Without substantial reductions in government spending including federal pensions, the dollar will collapse at some point. The world will not be able to absorb $100 trillion of new dollars. Essentially, this country is consuming far more than it is producing. The dollar’s collapse will bring widespread economic devastion wiping out savings and purchasing power. If governments (state and federal) still do not reduce spending, no one will accept dollars for transactions.
Sure there are assets. I have a couple of thousand acres on the Grand Canyon checked out and they’ll do just fine. BTW, the Constitution itself guarantees MY PENSION but it doesn’t protect national monuments, national parks, Obamakkkare or any of these other extraconstitutional gimcracks and geegaws.