Shadow Dragon: Caeda, Cain, Abel, but they're all pretty popular so they're basically in.
Awakening: Lon'qu, Tharja, and Priam. I know they want less sword users so I wouldn't be surprised if Lon'qu and Priam didn't make the cut. I feel like Tharja is popular enough to make it in though. Also maybe Masked Marth as a costume for Lucina.
Fates: Takumi, Elise, Azura, Hinoka, and Arthur. I can easily see Takumi, Hinoka, and Azura being added in due to importance to Fates and the fact that Takumi has a legendary weapon that would make for some cool attacks. I can also see Elise in based on War Cleric Lissa. I just love Arthur but doubt he'll make it in.
Other: DLC is always a possibility right? For the love of god please give me Ike and Nino. ;~; I'd also really want Roy, Alm, and Celica.