Just because it's possible to build equivalent software by vibe coding doesn't necessarily mean that companies will stop using SaaS. There are multiple reasons why...

First of all, many big companies pay a fortune to use inferior SaaS solutions instead superior Open Source solutions; possibly because one of their CTO may have received kickbacks or promises of a lucrative job at the SaaS provider as a consequence of this deal. There are a lot of politics going on behind the scenes when it comes to procurement.

Execs at big corporations are often looking for plausible ways to spend investors' money in a way that they can capture some of it for themselves. If they choose open source or they choose cheap vibe coded solutions; there is not much money changing hands. No opportunities for insiders to covertly monetize.

And then there are a lot of security implications to using a complex vibe coded app. The AI won't be able to identify the vulnerability in any decent sized codebase unless you know what you want it to look for.