I am expecting that vibe coding is just a passing fashion like many others in the software industry, but just in case it isn't another observation is that code being churned out in a substantially automated way will lead to the source code being closed. Because if you fundamentally don't care about the code or its quality then why even make it open source?

Making slop code open source merely exposes any organization doing that to ridicule (makes them look amateurish), but worse than that it also exposes all the security vulnerabilities which sloppy code creates. If you don't care about the code then why would you even bother to attempt fixing security issues? Under those conditions there would be more of an incentive to go for security by obscurity. Probably everyone reading this knows that such security doesn't work, but you have to put yourself into the mindset of a suit or scriptkiddie type of persona - someone who has no interest in code or its quality or maintenance, only its effects.

If vibe coding is here to stay (and I expect it isn't) then it's not endogenously sustainable but will be parasitic upon open source. Because there will always need to be "source available" to train the models upon. It sets up a license laundering system in which freely licensed software can be exfiltrated into closed security-by-obscurity software.