I thought of this also but I’m fairly certain Ozai would not waste the comet advantage and would at the very least use it to conquer Ba Sing Se, effectively winning the war. Aang would likely just remain frozen in the iceberg.

And if you think Ba Sing Se wouldn’t be the end because of the Northern Water Tribe, Zhao would probably have still carried out his invasion of the North Pole too. Nothing Team Avatar did seemed to directly effect Zhao’s decision to invade the North Pole, that was purely Zhao’s ambition and Aang just happened to be there, so I see no reason to think he wouldn’t do it if Aang never left the iceberg. Without Aang there to destroy the invasion force, Zhao would succeed and capture/kill the Moon spirit.

The last two major holdouts left in the world would be conquered/destroyed and the Fire Nation would have absolutely eradicated any sense of balance left in the world. Crazy to think how truly instrumental that twelve year old boy was in ending the war