The maintenance costs are kinda overrated: you fire up the LLM, point it at the code base and say "this needs fixing". I'd say that the maintenance costs of dealing with endless patches and fixes from a SaaS for features that you don't use is probably more onerous.

And generally we're talking about the situation where the SaaS customer is a domain expert in their area of expertise, but that isn't software development. They can use a system incredibly well, they just can't develop it. They have in-house IT folks to maintain their computers, networks, etc, and they're really just adding a couple of people to develop and maintain some applications via LLM to that team.

We're already seeing some of this, so it'll be interesting to see how far it goes.