1. They don't ban AI posts => probably a lot of low-effort (often correct) postings; reputation farming because why not; people trusting SO less; may as well skip the middle-man and simply ask ChatGPT directly
2. ban AI posts => how do they enforce this; conflict/complaints/annoyance when mis-flagged; reduction in answer submissions; plenty of generated (mostly correct) answers getting through; reputation farming; quality could still decline until people stop using SO (but maybe not as soon as 1).
3. put more effort into allowing correct answers (regardless of how written), penalize incorrect answers which appear generated => maintain higher quality bar; can sustain for a while until ChatGPT et al is simply just better to ask directly (but not as soon as 1 or 2).
I used up my free credits using GPT-4o the other day asking random stuff that I might have googled or Wikipedia searched before--it was more efficient and engaging. I could come around to paying $20/mo as I'd get way more value than I get from Netflix and a few other services.
A lot of sites are going to have trouble competing with AI so they may as well have the best AI for their domains to stay relevant. Humans will still be providing original content but most of it may be indirectly consumed by others. A lot of content wasn't accurate anyway so there will simply be more pushing an agenda or just selling stuff. Hopefully we will value quality and our preferred truths and there will be some competition to deliver that.