In terms of roster, there's plenty potential. Red Hulk and the Leader are currently at the Raft and there are other characters they could use such as Bullseye or the Punisher if necessary. For story, there are a lot of open plot threads, they could deal with the Skrull remnants on Earth, corporations such as Roxxon or AIM or Val's plan of invading Wakanda for Vibranium.

If the first one turns out well then sure

Though the * still means something and probably when that’s revealed the sequel might be different

I have absolutely no doubt they will.

So long as it DOESN'T turn into a disaster flick like DCEU's Suicide Squad, then it's likely.

If the film does well, sure why not. Thunderbolts* feels like a Black Widow 2 in the same way that The Marvels was Captain Marvel 2, continuing most of the cast's arcs along with Yelena seemingly being the film's POV character. Captain Marvel 3 seems less likely not because of the crybabies who couldn't handle Brie Larson or the character of Carol Danvers but because The Marvels was Marvel Studios' first legitimate financial failure so if Thunderbolts* makes money they will probably continue as a Thunderbolts 2 but if it doesn't, the characters will probably continue elsewhere

Probably, the cast is probably going to be vastly different from the first film and maybe people can get that True Dark Avengers film that people has been about ever since this film was announced.

If it crushes at the box office and fans are into the vibe, Marvel’s gonna keep it going. They love a good team-up sequel if it brings in that sweet post-Multiverse Saga energy. And yeah, the roster would be a big deal! Like, are we talking more of the original crew sticking around? Or will they swap in some newer, more chaotic faces? I could see them pulling in someone unexpected from the Disney+ shows. I just hope it doesn’t feel like a one-off detour and builds toward something cool. I’m hyped.