She is likely to marry Kovu at the end of Simba's Pride, but assuming she either didn't fall in love with Kovu (that whole betrayal thing could have wrecked that relationship) or if she never met him, and decided not to marry, would she still be next in line, or would the role go to Kion?
In short, does it always have to be a King, or could it be a Queen if the next in line is female and unwed?
This is a real poser because while Simba stated that Kiara is the next in line, Sarabi didn't take over for her dead husband but Scar got the new role (though who would have taken over had Simba still stuck around is a mystery too as he'd be far too young to take the throne at that point.)
I guess another way we could ask if an unmarried Kiara would be the next Queen is, what if Kiara WAS able to defeat Zira, but Zira WAS able to kill her father first before being taken down?
Would teenage Kiara take the throne, though that would mean, till she married Kovu, that there would be no King, would cub Kion take the throne, or would Nala take the throne (and still there would be no king.)