First, it would be nice to have a copilot variant that searched only my own work, so I wouldn't need to grep through other code I've written to get a reminder of how I solved a problem in the past.
And, speaking of the past ...
Second, I am old enough to have seen slide rules being replaced by calculators. This was a great addition to the toolbox, but it also had its downside: I've seen many students who have very clouded notions of significant digits, and many more who get quite confused with where to put a decimal point, when I ask them to compute something simple by hand.
Similarly, coding has been transformed with the advent of stack-like systems. There are two communities of coders now: those who learn a language and then can solve problems based on a solid foundation, and those who shorten the learning phase and code by web-search. The latter, it seems, are in danger of creating code that is brittle, limited, or downright wrong.
To the extent that copilot amplifies this habit of searching instead of thinking, I think it may lead to unreliable code.
So, sure, there are copyright issues. I think they have been well-discussed here and elsewhere. And courts may weigh in with new ideas. But my concern is with the reduction in code quality that may ensue. I'd love to see a discussion of the groups that are using copilot. If they are working on something I don't care about, then this is just a copyright issue. But if they are working on the "smarts" behind drug discovery, the control of dangerous machines, etc., then we have another issue, besides copyright.