Peggy had a life after Cap. She got married. It would be unfair to the character to fuck that up just so Steve can get what he wants. The way the character's been written, does that seem like a decision he would make?What if he got displaced in time and got back to WW2 without the serum. He gives up the Captain America title but can live in peace with Peggy. Happy ending and no more Captain America.
The point in time, around phase 2 and beginning of phase 3 when people were whining about Marvel not having stakes cause they didnt kill off their characters was annoying and dumb. But now we've come full circle and, apparently, characters should never die in a story?
Character deaths is still a valuable tool of storytelling. I was against it happening in the middle of their decade-long storyline, but now we're at the end. It's as good a time as any.