Honestly matchmaking only would immediatly kill the game for me, its the worst feature ever invented in online gaming. But I think the ranked system would need an overhaul since it was easy to trick it in Chaos Theory.
In term of gamemode I just want to see Story mode, which is basically already confirmed ofc since it's whats the game mostly is about and maybe a TAG mode like in Chaos Theory (deathmatch 3v1 with special rules).
Other than that I would like to see some old maps like Aquarius, Club House (Lakehouse is similar so we have this already I think) and River Mall.