Yuna is NOT CONFIRMED!!! (yay! I got here before KL!!!)
However Vinicent is, though there are no screens of him yet.
And Zanarkand would not work out for two very good reasons. TIDUS AND WAKKA!!!! First off they are on Destiny Islands, and Second they are too young to start that story yet. However it is possible she could be in, but a younger version possibly. HA I MANAGED TO SET THIS STRAIGHT BEFORE KL!!!
And also, IMDB is not exactly reliable, but KL could explain the reason better than me.