I agree.
Congress has no legal obligation to keep the benefit forumals unchanged!
Or to pay any benefits at all.
True, but I think you would agree that completely eliminating benefits wouldn't be wise or politically feasible. Thankfully, it's not necessary to stay solvent. The sooner we start modifying the benefit forumlas, the less abrupt and less painful the necessary cuts will be.
I'm pretty optimistic that a hybrid combining elements of Ryan's plan and the deficit commission's plan will eventually pass. Politicians on both sides are beginning to realize it must, and at the end of the day, it can be sold to the public. Underneath it all, the case is just not that hard to explain: the money to pay the promised benefits is simply not there, no matter how high you raise taxes on the rich.
While the urgency of changing our entitlement state cannot be overstated, I think the difficulty of the task is being overstated.