Idea about the new champion, Kalista

I have this idea about Kalista with her ability where she links herself with someone. I don't understand why it has to be with only one person through the whole game. Consider what happens if that person, usually her support, goes AFK or disconnects. Then she is without a ult for the rest of the game. Or if say that her partner isn't the very best Leona, Malphite, or Janna (sense those are the main three supports that go good with her) and she would like to link up with someone later in the game when it comes to team fights. Maybe she has a Soraka, support and you don't want to throw a Soraka, into a team fight, or she got trolled and was stuck with Teemo support.

Think about this. She already has a ability that gives her a ward, not only just that, but a moving one, that also screams and follows someone when they see them. So why does she really need that free trinket that most people get? Why not just replace that with the spear item that lets her pick her host. Make it a permanent, and it could have a cool down on it, like two minutes or so, so that she's not just changing a host every second. And maybe you could also give it affects for her stat-wise. Or be able to upgrade it so that the bond between her and her host are stronger or something. I and a lot of people that I've talked to have thought it would be a bad idea to just be stuck with one person through the whole game.