The interesting nature of this show is that both the Falcon, Sam Wilson and the Winter Soldier, Buck Barnes, have been Captain America at some point. In the comics, Sam had it first and then much later Bucky did. With this show, we have very little to go on, just speculation based around the characters announced for the show.
The show will need to fill in some of the gaps of the MCU and will probably be centered around Falcon proving not just to himself, but the US government that he is worthy. The formula is the written appearance of the US Agent. A person that the Government felt ‘better represented the Country’ than Steve Rogers. He has also went by the name Super Patriot and in both cases has had his showdown with Steve Rogers.
With the original Captain America in retirement, dead to the world, it becomes time for the Falcon to prove his worth to the nation. We even saw hints of that internal battle with Sam’s line in Endgame.
“Feels like it was meant for someone else.”
This gives the show its edge of him proving it. In a classic writing sense, it gives him battle with self and battle with the world kind of story. Zemo also returning to the MCU also gives them another person to conflict with. If I had to provide an educated guess it will be the US Agent acting as a rival hero or an antagonist, while dealing Zemo.
Another possible occurrence will be the rise of the Dark Avengers. This might be a theme being created behind the scenes in the MCU shows. The Dark Avengers is a group of Villains who pretended to be heroes for various reasons. Example being Venom posing as Spiderman. The group was originally led by Osborn who posed as the Iron Patriot, but with the Spiderman dispute that will probably be changed.
This show gives a lot of hope out there. It might even the lynchpin for the future of the MCU. This is not to attack the other shows, but consider that the second biggest MCU affecting movies was the Captain America movies. The first one giving rise to Shield, the second destroying it and outing Hydra. The last one splitting the Avengers.
If you can only watch one of the shows, I would leverage this one. This of course based solely on speculation.