I came to write the same comment as cool-RR. I'm not sure I ever copied a code block from an open source project. I copied plenty of code blocks from gits, stackoverflow and blogs. Those are the media that could be starved off by a massive use of Copilot.

There could be a problem for open source projects (and closed source ones as well) if Copilot could autocomplete with code from private repositories. I can't remember if it looks at them too.