37Signals tried that with once.com . Given they're now giving those away for free and haven't said a thing about it suggests it was an abject failure. What you're paying for with SaaS is outsourcing - deployment, maintenance, security, reliability etc are someone else's problem.

The code is the easy part but there's ongoing humans needed to make it work. If Agents get to the point they can genuinely autonomously SRE & patch a service everything changes but that still seems a long way off.