Also, it doesn't make business that much harder unless you built your business on being shady. See: the recent GDPR kerfuffle. For some it was just business as usual on May 26th.
They will because people will still buy their crap. There are plenty of lazy, misinformed, ignorant people who would do anything to keep happy-poisoning themselves, including fighting legislation meant to protect them.
And then they'll eat their babies. More realistically though they'll try to buy these companies to get their talent and patents. So in the end you banned the poisonous stuff, people who innovated made a lot of money and everybody's better off.
Maybe my hypothesis is overly optimistic but yours is comically grim. Do you think that we shouldn't have banned asbestos or leaded paints? That's exactly the kind of completely dogmatic rant I complained about in my sibling comment. "Things don't work perfectly all the time so let's do absolutely nothing".
Patagonia has switched to shorter-chain PFCs for many of its coatings (C6 instead of C8). They are also actively investing in research for alternative chemicals with adequate performance.
Nikwax, which sells re-waterproofing products, never uses fluorinated compounds and is a good brand to look for at the store.
Existing businesses might go belly up, but new ones will spring up to fill the post-regulation needs, and as long as there are businesses doing stuff the economy will grow.
There is much less evidence that the economy suffers under regulations than the opposite. Just look at California, for instance.
Interestingly that whole cryptocurrency epic we're witnessing is quite educative from that point of view, it makes the dogmatic "government = bad" position rather precarious and forces a more nuanced approach from either side.