Plus, considering many have theorized Captain America will die in Avengers: Endgame, maybe self-sacrifice will be the character’s ticket to his love and he’ll have a sequence with her in the Soulworld, as Thanos had with young Gamora at the end of Infinity War.
In fact, Peggy Carter is pretty important to the formation of S.H.I.E.L.D., which likely wouldn’t be possible if she becomes a ’40s era housewife.
Maybe Cap stays in the ‘40s or another point in the past.
Then again we’ve all seen Back to the Future and changing things in the past can completely change the future and there would be consequences there.