AI finding vulnerabilities in open source software is going to make it super unpleasant for a time. I expect there to be a shift back to closed source until we get through that period.
AI finding vulnerabilities and cleaning them up is going to be a budget problem for closed-source software, who have gotten used to ignoring vulnerabilities until somebody screams at them.
Closed source software isn't kept in a magical safe in a cavern deep beneath the earth, guarded by dragons. Half the people in your company touch it every day, and probably plenty of contractors.