Well yeah, but IDEs have code completion built-in as well. My point is, I think Copilot-style tools could do more that insert text. They could recommend lines

Well yeah, but IDEs have code completion built-in as well. My point is, I think Copilot-style tools could do more that insert text. They could recommend lines of code to remove, give you a quick keyboard shortcut to "place cursor in next file / line you're likely to want to edit", etc. IDEs can do some rigid versions of that (eg "Jump to next diagnostic", "Refactor", "Jump to implementation", etc) but Copilot could be the more general, more powerful version of these features.