I do think the current ecosystem of open-source libraries won't survive as it is, as AI screws up the incentives too much. But agents recreating the wheel for every project isn't practical either.
What I think we'll see happen is that AI vendors will create private ecosystems for sharing code. I.e. you subscribe to Codex and you get access to a suite of libraries that speed up your development process. Behind the scenes there'll be a mirror of the how the current ecosystem works, with agents submitting bugs and feature requests and a private swarm of agents working the most popular / high priority.
Not sure about this; what would be an incentive for AI vendors to do this ? More libraries used means less tokens spent, so it runs directly against their business model.
I suspect it will continue as it has. Where LLM's do use external dependencies, but quite a bit less than people do. Saving it more for the things that are complex and sensitive. They aren't perfect but overall it's better than the non-agent status quo (more dependencies, less re-implementing).