>>20390471I suspect Hilda might.
The developer who confirmed the timeline states that B2/W2 is happening approximately at the same time as X/Y.
Why make two Gens happen at the same time if there was no plan to make connections.
The Black & White story was never resolved. Hilda/Hilbert is still missing, and we don't know what the Original Dragon looks like.
So it's entirely possible that they could continue that story in Z, seeing as we are still in that time period.
As for Roxie? Maylene and Chuck appeared in HG/SS for example. Maybe she could be involved in a World Tour or something.
Roxie and Rosa could both show up in the Pokémon World Tournament too, which again, because of the timeline, could very well be a feature in Z.