In the ending of Deadpool 2, Wade dies shielding Russell and Cable spends his last time jump to bring him back. In my opinion, that is the cleanest way the film could have closed its argument.
Here is what happens in order. At the orphanage where Russell grew up, Wade talks the boy down from killing the headmaster, played by Eddie Marsan. Wade then takes a bullet meant for Russell and dies. The sight of a man dying for him is what makes Russell stop. Cable, who came to the present to kill the boy, sees the sacrifice and gives up his remaining time jump to rescue Wade. Wade survives, Cable stays in the present, and the group around Wade now includes Cable, Domino, Russell and others as allies.
Why does it work? The sequel opens with Wade losing Vanessa, so his death at the orphanage is the first time he risks his life for someone other than himself. Cable's turn matters because his mission was built on the belief that Russell would become a killer, and, perhaps, the film answers him with an act of kindness instead of an argument. I would also point to the botched parachute drop earlier on. Nearly all of X-Force dies in that scene, so the film has already shown that Wade's plans fail when he treats the job as a joke. The orphanage is where he finally stops joking, and that contrast is what the ending rests on.
It helps to compare it with Logan (2017), the other R rated spin-off in this saga, where an aging Logan is pulled into protecting a young mutant, Laura, and does not get a second chance. Deadpool 2 borrows the same shape, a worn out adult guarding a child with dangerous powers, but gives it a rescue instead of a funeral. Against Deadpool (2016), which is a love story with a revenge plot, this sequel is a story about found family, and the closing group of allies is the payoff.
The repaired time device afterward lets Wade undo some of his earlier mistakes, and the closing group sets up a possible continuation of X-Force and further team ups.
