Why are we talking about another sequel before "Deadpool 3" even drops? Well, Marvel Studios is known to plan their slates years — even decades — in advance, so there's no reason we can't speculate likewise. In this case, we want to see a tease for a fourth installment in "Deadpool 3," not just because it would be fun, but because many fans are likely assuming that the third entry will be the last, the capper on a stellar trilogy, and we want Marvel to put that to bed right away.
At the end of the day, there's really no reason "Deadpool" needs to conclude after three films, not while Reynolds still loves the character and still has a passion for killing baddies and cracking wise. With Marvel Studios clearly willing to allow "Deadpool" films to continue alongside the MCU, even in an R-rated form, we don't imagine they'd say "three is enough," especially not when they're raking in billions at the box office.
If anything, Jackman's addition to the series could very well reinvigorate Reynolds and Marvel, and get them primed for even more sequels, or spin-offs featuring Domino, Cable, and X-Force. If any of that is in the works, we want to see them say it in a post-credits announcement: "Deadpool will return."