YouTube would still be able to sell ads, but it will be the dumb pipe it was always supposed to be under section 230. This will be a much healthier situation with many regards.
I think the key thing is to stop considering that the current status quo is the golden age: there is so much abuse everywhere from misinformation and manipulation to wall gardens and monopolies, but somehow we've rationalized it and accepted it as a fact of life. What this law will do, is introduce some much needed rule of law in the digital landscape, and I believe create a healthier and even more competitive landscape.