tl;dr: It's possible, but unlikely, that we'll see other Hulks show up in the MCU. Those characters are all still around somewhere. However, they would likely fall under the banner of the Hulk's licensing rights. Right now, Universal doesn't have the rights to make a Hulk movie, and Marvel doesn't have the rights to distribute a Hulk movie, and neither really wants to help the other make money. Ergo, no Hulk movie.
As far as we know, there's no in-universe reason why any of the Hulk-related characters could not appear in subsequent MCU movies. As we saw in Civil War, General Ross is still alive (despite a possibly-golf-related heart attack) and serving as the US Secretary of State. Betty is also still alive as far as we know, though we have no idea where -- presumably, she’s back to whatever she was doing before The Incredible Hulk. (We've heard nothing about Jennifer Walters at all). There were also hints of Hulk villains like The Leader, and as far as we know, Abomination is still around and in army control.
However, from a real-world perspective, those are all very unlikely. The main reason is that Marvel has a deal with Universal Studios regarding the Hulk characters, that is separate from their deal with Paramount for all the other MCU movies. The crux of the deal is that Marvel owns the characters' licensing rights, but Universal owns the film distribution rights, meaning they'd take a share of the profits.
Disney has since obtained all of the distribution rights back from Paramount, but their deal with Universal for Hulk still stands. Disney, for obvious reasons, isn't too eager to share movie profits with its main business rival (it's probably already mad enough that Universal gets to keep using Marvel characters in their theme parks).
So, unless Marvel really really wants a Hulk movie, or Universal gives up and sells the rights back to Disney, we're not likely to see a Hulk solo movie for a while. And given that those characters are pretty unique to the Hulk universe, it's unlikely we'll see them showing up anywhere else in the MCU.