No doubt. Perhaps they even could have made it to retirement on the mango farm in the South Pacific.

The first time I played RDR2…without knowing anything about the story (including even other red dead games) I knew even then it was a terribly bad idea to rescue Micah from Strawberry.

Right off the bat I despised him and knew he was a terrible person with his first racist comment. If I had full control of Arthur there’s no way I would have rescued him. And even if I had saved him there were a hundred opportunities after that to deal with him before it was too late.

Nobody but Dutch would have missed him and Dutch would have got over it soon enough. So long as Hosea was around he’d have kept Dutch from going off the deep end. They could have made it.

Not by much, but yes.

Yes... but you're probably looking at maybe an extra few weeks, at most. The game flat-out tells us right at the very beginning that the time of the Old West is nearly at an end, and the few remaining outlaw gangs are being hunted down and destroyed. The problem the Van der Linde gang are dealing with throughout most of the story is that civilization is now popping up everywhere, and they can no longer just run west, beyond the settled frontier, to escape the law.

The other problem is that Dutch is unraveling faster and faster over the course of the story. Micah plays into that a bit, by validating Dutch's actions and telling him "You're doing a great job, boss!", but the decline was happening with or without Micah, and even if he wasn't there, members like Javier and Bill would still be around to blindly follow him and rubberstamp all his ideas. (I don't buy that Hosea would've been a calming influence, because he couldn't change Dutch's mind on taking revenge on Bronte, and there's no evidence Micah was on the other side of that, pushing Dutch to do it.)

It seems Micah convinced Dutch to go thru with the Blackwater ferry job that kicked off all their immediate problems, so in that sense: yes, the gang would've lasted a bit longer without him. But having civilization and the law pressing in on them harder and harder from all sides, with no great options to run to to get away from them would continue to fuel Dutch's desperation and bad decision-making, and it was inevitable that it was going to turn out poorly... and sooner rather than later, IMO