I think as long as AI isn't literal AGI, social pressures will keep projects alive, in some state. There definitely is something scary about stealing entire products as a mean for new market domination - e.g. steal linux then make a corporate linux, and force everybody to contribute to corporate linux only (many linux contributors are paid by corporations, after all), and make that the new central pointer. That might be worst case scenario - then Microsoft, in collusion (which I admit is far fetched, but def possible), could completely adopt linux for servers and headless compute, and enforce very strict hardware restrictions such that only Windows works.
I suppose the idea would be, they don't have to maintain it: if it ever starts to rot from whatever environmental changes, then they can just get the LLM to patch it, or at worst, generate it again from scratch.
(And personally, I prefer writing code so that it isn't coupled so tightly to the environment or other people's fast-moving libraries to begin with, since I don't want to poke at all of my projects every other year just to keep them functional.)
Even in a world with pure LLM coding, it's more likely that LLMs maintain an open source place for other LLMs to contribute to.
You're forgetting that code isn't just a technical problem (well, even if it was, that would be a wild claim that goes against all hardness results known to humans given the limits of a priori reasoning...)
It is just an optimization that makes sense -- writing an OS that is compatible with all sorts of hardware is hard, let alone one that is performant, checked for vulnerabilities, etc.
Why would each gigacorp waste a bunch of money on developing their own, when they could just spend a tiny bit to improve a specific area they deeply care about, and benefit from all the other changes financed by other companies.
So you have direct competitors all contributing to a common project in harmony.
It would just simply not make sense for them to let other companies' improvements go out of the window, unless they can directly monetize it. So it doesn't apply to every project, but especially these low-lying ones would be safe even without any sensible license.
Even if that's the ideal (and a very expensive one in terms of time and resources), I really don't think it accurately describes the maintainers of the very long tail of small open-source projects, especially those simple enough for the relevant features to be copied into a few files' worth of code.
Like, sure, projects like Linux, LLVM, Git, or the popular databases may fit that description, but people aren't trying to vendor those via LLMs (or so I hope). And in any case, if the project presently fulfills a user's specific use case, then it "going somewhere next" may well be viewed as a persistent risk.
The advantage of decoupling from supply chain attacks is so large that I expect this to be standard practice as soon as later this year.