Well, those are some sad news. I do understand that Versus was just concept, however they showed it too early and made it feel like it was not. After Tabata replaced Nomura we were told, as far as I can recall (but I may be wrong), that there won't be a lot of changes and that the story will remain as it was in Versus. First the cut off party switching, which was big change and now they cut off Stella, because they "found it increasingly difficult to make sense of Stella’s character and role within FFXV", which means that they changed story, too.
Personaly I liked Stella more, she looked like strong female character, that I enjoy so much. Luna, on the other hand, looks so far as her opposite.
That being said, I'm still looking forward to FF XV, although I'm not as excited as I was and I feel little dissapointed. And I know that me complaining won't change a thing, but I felt a need to express my opinion somewhere.