One other feature that I don't find likely to be implemented but would be awesome is separating the progression from the player level and allow us to rank up even in zombies/coop that way we don't just all need to be rank 55 everywhere and we could rank up in zombies this could also allow mod/servers use this system to allow there own progression.
I do realize a mod could do this but if Pluto doesn't allow multiple mods loaded at once this kind of stops people from using other mods. Plus it would still be nice to allow people to rank up either way.