With Strelitzia...I feel like she could come back, yet at the same time I'm skeptical...
Like, it's highly possible that they could explain her coming back with "oh, this happened and that happened, so she's still alive yay!".
But unlike with other characters it isn't really a special case with a bunch of rules added to make it more complex than simply saying "oh, they died."
Like, Xion presumably returned to Sora, and it's possible that people could remember her again. I can't even be bothered to talk about Terra's situation.
Strelitzia just seemed like a normal person. Other than wanting to be friends with the player she didn't seem to be anyone special. It was a case of a regular guy killing a regular girl. That is, unless the update reveals stuff about Strelitzia and the whole assassination thing that we didn't know about.
At the same time I do want her to come back, and it would be cool having her get her revenge like a badass with her new black coat. And I thought that the hooded figure could possibly be Strelitzia because of the little bit of hair you can see in the picture, not to mention the thing about the flower the figure is holding could be potential foreshadowing.