Well, considering the last two years have been Roy + Roy's potential wives and Male Robin + Male Robin's exclusive potential wives, I half expect them to keep up that pattern with another male character with multiple marriage options. I suppose that means:
-Hector. Serra, Florina, Farina as his potentials. Maybe Sue and Rath to round out the banner as a Harmonic unit, just to give Roy his final potential bride who happened to be left off on his banner.
-Ephraim. L'Arachel and Tana (Dozla or Innes as potential Duo partners?)...with Eirika and Myyrh tagging along as non-romantic options.
-Chrom. Sumia, Sully, Maribelle, Female Robin, random villager.
-Corrin. Who are Male Corrin's exclusive potential wives, again?
-Byleth. I have no idea who else they'd pick since any of the women can marry Byleth.
-Alear. As with Byleth, I have no idea who they'd pick. Celine, Ivy, Yunaka (she'll be the new Dorothea!), and...eh, someone.
Sacred Stones was just used as the game focused on for the Valentine banner, Awakening was used for this year's Anniversary/child banner, Blazing Blade just got a heavy focus on the Fallen banner, and we just got a Fates banner. I suppose that means Three Houses and Engage are a little more likely to be focused on than any of those. Unless, of course, they don't care and use something like SS anyway, or if they break the pattern of the last couple years and throw something like Mystery of the Emblem or Genealogy of the Holy War at us.