If they do a Wasteland 3 I really think that they ought to make the main faction someone else but the Rangers. The Rangers can still be in it, sure, but I'd rather explore a faction who's goals are a bit more than just "let's try to be the good guys". That's not to say the Rangers don't have some moral ambiguity to them, of course they do, it's just not enough for me. I mean, twice now the Rangers have been the main guys. If they do a third game where they once again are the main guys then that might become too much of a staple for future Wasteland games and they won't be able to let a different faction take the spotlight without backlash from fans.
There are other factions out there, let's explore them.
If Rangers have to be the main guys I'd prefer it if the next game starts out in LA and focuses on Wade Woodson's attempt to make the Boneyard Rangers (they ain't in a desert yo) a force to be reckoned with that can truly defend the people of LA. It'd explore the aftermath of Wasteland 2 where certain choices are made canonized by the writers and the ultimate goal would be that LA, no matter how hard you try to control it, is something that cannot be put on a leash. It'd lead to things escalating with new groups that rose from the ashes of the old, from radiation cloud beginning to disappear around the edges of LA which opens up a path to a new area where different powerful factions come through, eager to explore LA. It goes to the point that it feels like everything is going to fall apart if they don't get better support. With radiation beginning to disperse you're tasked with using a vehicle designed to protect its operators from radiation and go to various rad-free pockets to see if a new base of operations can be set up, where the Rangers would be safe from the enemies they've made and to organize and prepare for a counter-attack against these new foes.
That'd be interesting to me. But the Arizona Rangers? Bleh. We've had two games with them already, it's time to move on to a new faction or to explore a different kind of Rangers back in LA.