Let's say that one of these happened:
Timon and Pumba decided not to rescue Simba as a cub and he died in the desert.
Nala killed Pumba and possibly Timon, and Simba either kills her in retaliation before recognizing her or else is too angry at her to go back with her.
Simba couldn't bring himself to go back to the Pridelands, even with the encouragement of Mufasa.
Either way, Simba doesn't come back. I'm curious, what's the likely outcome:
1.) Hyenas (loyal to Scar) vs. Lions (opposed to Scar), survivors leave if lionesses win and survivors starve to death if Scar wins.
2.) Some hyenas (probably not in Shenzi's inner circle) and some lions (all opposed to Scar, and likely led by a very fed up Sarabi) vs. Hyenas (Shenzi's group) and lions (Zira's group) (loyal to Scar), survivors leave if Scar loses and survivors starve to death if Scar wins.
3.) The hyenas (minus Shenzi, Banzai and Ed) and the lionesses (minus perhaps a few like Zira who are cultists) all revolt against Scar. Perhaps the other hyenas turn on the ringleaders, exposing the plot that Scar had to kill Mufasa and that the three ringleaders were the only actual participants in causing the stampede or trying to kill Simba in the Elephant Graveyard. The Scar loyalists are overwhelmed and killed, as is Scar, and the survivors of the fight work together to survive, though the Pridelands doesn't have a king anymore.
4.) No fight occurs. The hyenas and lionesses with any sense eventually desert the Pridelands and Scar and his remaining lionesses and hyenas starve to death. The Pridelands become a wasteland like the Elephant Graveyard.
5.) Scar somehow dies of natural causes, for whatever reason, before everyone starved to death, and Nuka, being the eldest, and Kovu too young, becomes the new king, and he actually does ok, with Zira the de facto leader. Possible conflicts between Zira's/Noku's pride and the hyenas may occur as the hyenas and Scar made the alliance but there may not be such a strong bond between Zira and the hyenas.