This is a great idea! “chat completion” is basically what chatgpt is built to do–at least, that’s what the API calls it when you ask it to respond to a prompt. What do you have in mind? Something like “press tab to complete” a sentence?

FWIW the programming world has this already in the form of “github co-pilot”: https://www.youtube.com/watch?v=hPVatUSvZq0