Underwater combat is never coming back, adding a Z axis to a game that only ever had it accessible to players once over its 20 year history with the most recent game, isn’t a pattern for the future it’s a novelty. Plus in the same game, that being RISE, yes they added a z axis but also they introduced a new subcategory of monsters that I’m gonna dub “sky leviathans”

Sky leviathans being Narwa and Ibushi, they literally swim through the sky like eels/seahorses, I can see then expanding more on that concept of mixing underwater creatures with balloons so they can “swim fly” rather than have a complete separate mechanic that changes how a player’s moveset works between environments