This was the "Locked Box" that Al Gore got mocked for on SNL 26 years ago. So people saw it coming and were trying to fix it then. And it was the Democrats trying to fix, it is not a "both sides" case. There is one party trying to destroy Social Security, and one party trying to fix it. I encourage anyone to not take my word for it, and conduct some basic research of their own.
Anyway, the crisis is that there is less income than distribution. So we collect debt (unlikely, given appetite for US debt after the last 20 months or so) or reduce payments.
Since many social security recipients are wealthy and not at risk of poverty, what will happen is likely some sort of reduction after means testing. It is not ideal, but entirely because fiscal choices of America's collective fault.