Want to run your own simulations of potential changes to Social Security such as raising full retirement age, raising or lowering benefits, lifting the FICA cap? Take a look at the Penn Wharton simulator.
It's interesting that the model doesn't even allow you to look at the effects of completely removing the cap on the FICA tax. The model only allows you to raise it to $400,000. Penn Wharton seems to believe that's completely off the table.
If you're a fan of raising full retirement age or fiddling with COLA, be warned. Neither gets you very far. You're going to have to do a lot more than that.