I don't think that's a terribly good statistic to use in an argument against privatization.
Try telling any senior today that their benefit is going to be cut to 78%.
So, what you're essentially saying is, we're good for another generation, and then the next one after that is going to have to think of something....
What I'm saying is that we have 27 years of modest tinkering to fix Social Security to the extent it needs any fixing without blowing the program up and that ridiculous comments about SS "not being there" are stupid.
Moreover, 78% of scheduled benefits is actually quite a good deal compared to the benefits today's retirees receive based on the way in which benefits are calculated.