My MCU theory is that this is also Steve's last scene after Avengers: Secret Wars. Old Steve is arriving from the 616 that will be created by Secret Wars.
What's your crazy MCU theory?

Doom isn't a Tony Stark variant. The Tony Stark we knew is the only good Viktor Von Doom variant. What Doom wants more than anything is to be revered as the savior. The only way it happened for him was when he was known as something else.

That nimble guy in the red suit... I'm convinced he is the chemistry student known as Pater Porker. They're never in the same room .... what are the odds

By that logic, I must be Magneto because we've never been in the same room simultaneously, either. Hmmm... time to try some things.

Magneto doesn't have a secret identity though?

Gwenpool is secretly directing all the movies in order to save her universe from the harm caused by our own.

I don't think we'll see old man Steve, so while it's probably right I don't think we'll get a reference to this scene. I also think when Steve goes back in time to live his life he already knows he's giving the shield to Sam. I expect instead during the film Sam will see Steve without the shield, try and give it back to him, and Steve will refuse since he already gave it to Sam. (I do still think Steve will don the shield at some point, but he'll return it to Sam as soon as he can.)

So how did it go ??