Something I look forward to, though it could take a few years, is for someone to train a family of state-of-the-art chatbots where each uses a corpus with a cut off date of 1950... 1900... 1850.. and so on. How fascinating it would be to see what words and concepts it would and would not understand. That would be as close to time travel as a person could get.

It exists! Showed up on HN a few months back: https://github.com/DGoettlich/history-llms

Only from 1913-1946 though.