It’s fine not to know. However I feel the larger issue is Marvel has put so many pieces (characters) on the board this saga that it’s just become almost exhausting getting introduced to new characters all the time and then never hearing from them again. What happened to Shang-Chi? The Eternals? Hell, even Spider-Man. We likely won’t see from him until next summer at earliest. I could go on in this category.
I think it’s probably reasonable to deduce that the elder statesman of the MCU (at this point) will be central figures whether officially an Avenger or not.
So by that logic we’re looking at Spider-Man, Doctor Strange, Captain Marvel, Hulk, Thor, Ant-Man, Black Panther, and if I were to take a wild stab, I’d guess Deadpool & Wolverine as well with the Fantastic Four mixed in.