Not necessarily, other games like Battlefield do way more than 20-24 players in maps bigger than the planets in Destiny. Its possible, and I think likely for Destiny 2, since Bungie has a history of experimenting with larger scale multiplayer modes. They initially wanted Halo 2's multiplayer to be larger and more objective based, and I think part of that manifested in Invasion. I also think a bigger map would better fit the mechanics of the game, so that the tiny maps we currently have aren't a constant ClusterBlam of Supers, Grenades and Heavies.