According to the claim in this reddit thread: https://www.reddit.com/r/ChatGPT/comments/13xbd9n/1_million_tokens_context_window_is_coming_this/

"Longer context windows — Context windows as high as 1 million tokens are plausible in the near future."

How plausible is this?

This market resolves YES if a version of GPT4 with a 1 million or greater token window is released this year.