Exactly. A game that every play has a cutscene and repeats itself won't survive only by adding more weapons. It needs more life, more exploration that could be by given random encounters with mini-bosses or special mobs, time events that change the map, and limited quest & rewards. Be it skins or weapons, or any customization and then expand and repeat.
There would be a lot of options to implement and give new life even without a new campaign (truth be told all older players must be as interested in the locals' campaign and Shamash coming to the game with his Thanos as appearance)
