For me is definitely Grandin 2! I didn't finish this game in dreamcast! I hope I can in this port over! And finally Shenmu..total awesomeness!!
Probably the rest of the Phantasy Star series and the Shining Force series. Brings back a lot of fond memories.
Honestly, I think I'd be more than content with just Streets of Rage 1-3 coming back. Oh, and a remastered Sonic 3 and Knuckles has to happen. Unrelated: Sonic Mania better make it to iOS!
Streets of Rage 1&2 should be a lock. Going by the tape SEGA sent me, we can at least look forward to Space Harrier, Outrun, Super Hang-On, Shining Force 2, Columns, Vectorman, Golden Axe, and G-LOC Air Battle. I'm sure the usual suspects like Streets of Rage, Gunstar Heroes, and so on will be coming, too.
Street of rage and Golden Axe, definitely (as long as there is MFI controller support) Virtua Fighter series!! �� If they can run Namco's sword fighting game, then definitely this. I would expect it to come much later, and would be glad to pay a bigger premium.
Golden Axe I-III more Phantasy Star series games and Shining Force for sure also these revenge of Shinobi, King Colossus (since it never got an official outside Japan release), outrunners, dragon crystal, and dragon force