> will we start seeing a formal split in open-weight model development—specialized “reasoners” that rely on tool use for facts, and “knowledge bases” tuned for retrieval-heavy work?

My bet's on the former winning outright. It's very hard to outrun a good search engine, LLMs are inherently lossy so internal recall will never be perfect, and if you don't have to spend your parameter budget encoding information then you get to either spend that budget on being a much better reasoner, or you shrink the model and make it cheaper to run for the same capability. The trade-off is a more complex architecture, but that's happening anyway.