The contract is me guessing, but I think you're probably looking at $6 million+ on the next deal, especially if ADA hits certain "magical" pleateaus such as 20 goals and 60 points. As if this post, he's on pace for both and (I believe) has scored in excess of 50 points over his last 82 games.
I have a hard time seeing the Rangers move him, unless they are absolutely blown away by an offer. They've invested a lot in him to get to this point. And frankly, the plateau he is hitting puts him into a very exclusive club. If he was hovering around the 45-50 point range, I think there's a greater possibility the Rangers would move him --- especially with Fox and Lundkvist in the organization. But at his current level of production? I just don't think they have the balls to do that.
As for the comparison to JT, I just think they're on very different levels for their respective positions. If Miller was posting 70-80 points as a wing, I don't think he gets moved. That's probably the point we've reached with ADA.
I also don't think his personality and past experiences have little or no impact on how the Rangers view ADA in 2020. Literally no one I've talked to within the organization, or with connections to the organization has ever mentioned a problem with anything related to his world views or things of a personal nature. There have been things they've wanted to see from him on the ice, including how to channel his emotions. But almost to a person, everyone has cited his personality type as something the Rangers value --- especially with the proper guidance. So I do not believe that is going to be a factor.
Right or wrong, players are held to different standards then coaches or executives --- primarily because they aren't seen as being in positions of power where they can completely derail someone else's career. I think if anything ever came out, I think ADA would be advised to own it and then the team would likely rally around him and share stories about the person he's become. Granted, that's me speaking as a public relations executive. But I am willing to bet that a similar approach would be taken by the Rangers current comms teams.