During development we were told that late game paths have a big effect on the story and endgame.
Mechanics aside, the Swarm certainly fulfils that promise with you doing the rest of the game, including the crusade, alone with your swarm.
Other paths though do not change anything. For gold dragons the game goes on like normal like nothing happened.
Imo every late game path (except Legend) should remove your companions and the crusade system and replace it with something else. That doesn’t mean they have to die or disappear forever, but become NPCs instead.
As dragon you should turn over the the crusade to whoever you trust, leave your companions and recruit some other dragons of various colours (or depending on your decision kill them and steal their hoard for power) and with them attack the threshold.
As devil you should rally hell and Cheliax and lead them to victory while Mendev and your old companions stand by and watch (maybe keep Regil as a servant).
Even Legend should transform the crusade somewhat, making it a grand alliance of mortals, attracting all kinds of people. Pirates from the Shackles, people from Osirion, Quadria, Numeria, Pathfinders, etc. with several diplomatic quests, etc.
Tl;dr All late game paths should alter the late game in the way the swarm does. Maybe even more so when Owlcat gets around to improve Act 5 (which means also improving the swarm content of course).