I would love them leaving Emerald's BF exactly the same, since it's my fave battle facility. I'm especially looking forward to seeing the Pike and Pyramid in 3D if the Frontier's included. That being said, I wouldn't mind seeing the Battle Roulette/Arcade and Battle Castle reappearing, as those were my fave places in PtHGSS's BF ;o; However, I can't see them replacing any of the buildings in Emerald's Battle Frontier nor can I see them being added, so I wouldn't be upset if they weren't included.
Also, as mentioned in the thread about the PWT, it would be cool if the Dome could be merged with the PWT such that you could do regular Dome battles, and upon fulfilling certain conditions (or not fulfilling any) you could do PWT challenges and fight Gym Leaders and Champions and rivals and whatnot~