You don't specify where you are flying but I suspect IAD-CPH.

If you get bumped at IAD then you will fly UA or LH with 99% certainty. Then you will earn more *A miles. In the summer they might send you up to EWR for the midnight flight.

I know someone who got an involuntary reroute to Turkish airlines instead of LH but still got her UA miles for the original routing. Maybe it's different if it's voluntary vs. involuntary....