Captain America and Blue Marvel probably isn't edgy enough.
But U.S. Agent and Blue Marvel could work. They are the perfect embodiment of the American experiment. Only the power dynamic would be on the other foot. But deep down, both men share quite a bit in common.
There are probably a million ways to make Blue Marvel more popular. But popular and well-liked aren't necessarily one and the same thing. Marvel's fanbase will need more time to come around to liking Blue Marvel. And no, I don't mean to suggest that is a given.