High cost per-seat SaaS will die.

SaaS itself won't because it will always be easier to use existing software vs vibe code your own. The reason people are starting to roll their own is because with AI they can, and many SaaS products are still priced as if code is expensive.

I suspect in the future SaaS products may need to move to advertisement models rather than charging per seat. I also suspect successful SaaS products of the future will be much smaller and much more niche projects, with much smaller teams maintaining them.

This will take many many years to play out however. A large company using Salesforce today is going to find it extremely difficult to switch even if they want to.