The portals to hell have legs and health bars in Diablo 4: Vessel of Hatred's Season of Hatred Rising
Demons can be anything they want, apparently. In Diablo 4's next season, which starts on October 7, a massive creature called the Realmwalker will stomp around Sanctuary with a portal to hell on its back. Defeating it will send you into a dungeon with more portals and new seasonal potions to help fill your inventory with loot.