They're going to have to do both. They won't want to, and they'll scream about it, but they will.

They're not going to have to do both. That's why I mentioned the Bush and Trump tax cuts - to illustrate that addressing this doesn't require going back to the 90%+ marginal rates of the 1950's, but instead going back to a system where the highest marginal rates were in the high 30's rather than the mid 30's.

Painful medicine? Sure. Raising taxes for no expansion of government services is no fun. The public will hate it, and the GOP will make political hay out of it for years and years. But if the choice is between rolling back taxes to 2001 vs. cutting benefits, Congress will choose the former.

Bear in mind that "cutting benefits" also takes the form of freezing increases also.

Also a political non-starter. Touch SS COLA and you'll have a riot on your hands. And we've all seen how the efforts to restrain Medicare spending increases turned out - a constant string of "doc fixes," ending with the law just being changed permanently. All with bipartisan support. Freezing spending increases on veteran's benefits is similarly a non-starter. Support for Medicaid and military spending is slightly more partisan coded, but at the end of the day those aren't going to be on either the chopping or freezing blocks.

Older voters are powerful, and Trump has neutered the faction of the party that supported cutting entitlements. Congress is simply not going to choose cuts or freezes instead of choosing to raise taxes. There might be a fig leaf - a nod to trying to do both - but nothing material. Congress will raise taxes in lieu of cutting benefits.