I would personally like to see this. Especially if they decide to make the movie more "mature" like with The Jungle Book.
-an expansion on the mythology and lore of the Pridelands
-More of Scar's reign [I know a lot of people have mentioned this already.]
-bringing in Mheetu would be so awesome, even if he only had a minor role
-that deleted scene where Scar tries to make Nala his queen before she leaves to find Simba, I mean, they included it in the musical, so why not the remake as well? I believe it was the "Scar's Madness" scene.
-Any other deleted scenes
-Just more Scar, he's awesome. I'd like to delve into more of his POV
-This is very unlikely, considering that even if the movie did well, they wanted to do TLK2 also. But even so, what if they brought in Zira for an appearance, and maybe Nuka since he was his only true heir. As I stated above this could be if it had more of Scar's view.
-In the end, what if there were two cubs instead of one? Since now it's clear that the original movie had a sequel? The movie could at least acknowledge that Simba and Nala had two cubs, whether the second cub is either Kion or Kopa. I mean, I know Kopa isn't really canon even though I like to think he is, but I've also kind of forgotten if TLG is canon to the movie universe. XD
I know budget and time is essential to consider, but I wouldn't mind if they cut some of Timon and Pumbaa to include some of these.