This is a pretty far-fetched idea, considering the activity and progress rate of this game, but it's still nice to fantasize about
A Sunset Riders Mod.
Most things for it are already implemented, or in progress (rideable/moving horse, etc.). Some tweaks for spawning enemies once along a long path, dropping large sparkly coins, bosses, moving stage coaches/ox carts, stampeding bulls, etc. would be needed. As well as multiplayer campaign/mission with a linear map-change.
Just something nice to dream about for now...