I actually really question this, was it truly outlandish to imagine what we have now? We had Google, Stackoverflow etc, yes there new elements to it, the data was there and accessible, but I don't think LLMs are unimaginable?
There were GANs which e.g. produced realistic faces, but these were restricted to one subject matter only, not something like Midjourney V5 which makes basically every picture whatsoever based on a text description, just with occasionally one to many limb. People were so impressed with Dall-E 2 that it is hard to imagine how extremely impressed they would have been with Midjourney V5 (without having seen Dall-E 2 first).
If you told HN commenter three years ago (for context, that was when COVID took off) that we would very soon have technologies like ChatGPT-4 then, I'm sure, that would not have been taken seriously.
Everyone and the researchers themselves were shocked iirc; all this higher order reasoning emerged from being a next token predictor, yes that was the outlandish part.