These are also many of the most looked at, most often fuzzed, SAST scanned, valgrind'd things in the world.
I really don't think it will be as bad as all that. We have not seen Apache, Nginx, etc pwnd like this, or OpenSSH, or Bind, or postfix ...
I could go on. I think the actual posture and condition of most of these project is far better than you apparently expect. (I guess we are going to see who is right).
What AI is finding is stuff the other scanners miss, which is stuff where there is a clear temporal component. We are going to see races, toc-tou, probably more stuff like these PHP issues which if I understand correctly is a use-after-free or something you could at least force into that taxonomy.
So there are going to be new bugs found, even seriously impactful appearing ones, but the reach-ability and chances of successful exploitation outside laboratory conditions is going be low... Do they work when it is a VM on you lab server you can hammer away at with 1000 threads yes; when there is a AWS ELB in-front or a waf that has any impact on request ordering or pipe-lining, good luck..
I am not saying people won't be spending more hours patching over the next year or so than they have been, they will but the sky probably also isn't falling