When you sell a service, it's opaque, customer don't really care how it is produced. They want things done for them.
AI isn't killing SaaS, it's shifting it to second S.
Customers don't care how the service is implemented, they care about it's quality, availability, price, etc.
Service providers do care about the first S, software makes servicing so much more scalable. You define the service once and then enable it to happen again and again.