I really don't understand why Disney has yet to mention Kovu, as he is vital to Kiara in her role as Future Queen.
It would be very nice for Disney to confirm or deny what many of us fans fear may have happened with Sarabi.
They could give Sarafina an appearance where Kion askd her advice, to witch she could respond "HMMM" before getting interrupted by something or someone. Another thing they could do is have Kion seeking advice form Kiara, Kiara could show up late to her meeting with Kion and she could say "Sorry I'm late, Kion, I was visiting with Grandma Sarafina. You know how she loves to talk." To which Kion could nod his head.
I don't know what role an appearance by Vitani could play. Perhaps she could give Kion some info on the Out Lands.