The things I want to do most in Cyberpunk 2077 are to explore the world and experience some of the amazing writing I expect to see.
I want to see how CD Projekt Red has managed to create this different type of RPG where they have to create everything from scratch and give options (gameplay-wise) for different types of characters since not everybody is going to play as Geralt of Rivia.
A bit off-topic but; I also want to see how well they have made the first-person combat work and I hope they have taken hints from some of the best in the business of modern first-person games (Arkane Studios, MachineGames, Respawn Entertainment, etc.) and made it play and feel as good as possible. I know the game is not an FPS (it's a first-person RPG) but even then, it's really important to make the movement, shooting, and everything around them FEEL good. Especially as the game seems to have different 'abilities' that affect movement. Also, customizability (of keybindings and FOV among many other things) is extremely important.
What I'm trying to say here is that, more than anything else, I wish to see a great open-world first-person RPG with a beautiful/deep/immersive world that is fun to explore, W3 level writing, and good movement and shooting mechanics. The Witcher 3 is still the best video game of all time in its genre and I hope Cyberpunk 2077 will achieve the same.
While my expectations are very high, I can settle for less. A man can dream, though, right?