People stopped smoking immediately, and cigarette sales tanked. The cigarette companies laughed (with all the phlegm in their throats and lungs) and sales came back 1-2 weeks later.
I suspect in a few months or a year companies with vibe-coded replacements for SaS products will find they need to go back: But, just like how many less people smoke today than in the past, the writing is clearly on the wall. At some point someone will figure out how to replace SaS with AI; it's just going to take a lot longer than many think.