the self-limiting target audience of adults-only. Deadpool being pulled into the MCU may help. It honestly stands a decent chance of approaching $1B in revenue, but I just think it will be hard pressed to get any higher than that (Deadpool 2 got just under $800M).

Joker made around $1B in revenue, and its sequel could hit similar. Again, it's hard for an R rated movie to get much more than that. Of course I say much more than $1B as if that's a pedestrian number. It's a huge number that I think those film producers would be thrilled to reach. It's just that I think the #1 spot will be a bit higher.