I thought it was pretty obvious he was going to be the next Cap after End Game (? The one where they finally beat Thanos). Even if you hadn't seen Winter Soldier, it was super obvious foreshadowing in Endgame.
I vaguely remember big boss being a woman in MGS3 but then in 5 suddenly they're a man?!
In the comics world, almost every superhero has had different people using the name at different times. But then again, they almost always bring back the original eventually, too...