The A-wing and B-wing are very much the focus of Rebel Aces, so I'd be hesitant to put them in another box. Besides which, neither are especially useless, and the B-wing has the advantage that any new crew or system release can theoretically be used on it, so it's easy to slip 'cookies' for the B-wing into other packs.
Between Guidance Chips, Bomb Loadout and assorted new turrets, the Y-wing has three distinct roles it can perform well.
You also don't need to include any new y-wings to increase its options - if the E-wing is in the box, it justifies 2-3 new astromechs, and you can easily 'slant' one or more to supporting the Y-wing rather than the X-wing or E-wing.
I'd say E-wing and T-65 unless there's a specific T-65 pack intended to support Rogue One. Ghost and Maarak Stele have shown that FFG are accepting putting the same pilot in multiple packs, so a Corran Horn X-wing would be a logical repaint.
I think the 'Rogue One' thing is key. FFG co-opted nearly an entire wave for Episode VII, even releasing a new core set. I doubt they'll go QUITE as far for 'Rogue One', but it'd be insane to assume they aren't going to try to cash in on that movie tie-in as much as possible for what they are spending for their license.
(Indeed, you don't even need to assume - they've already confirmed they are doing 'Rogue One' products)
So the question is - will the 'Rogue One' release be JUST T-65s (it's certainly all we've seen in the trailers to this point), or all the other fighters at Yavin base, too? In which case, the 'Rogue One' would end up most likely being another T-65 and another Y-Wing.
Either way, I can't imagine FFG passing up 'Rebel Veterans' as a pack, and a T-65 and/or Y-Wing showing up in 'Rogue One' means it would be a bit odd to show up in 'Rebel Veterans'.
So my theory at the moment:
- This year we get a 'Rogue One' expansion, with a T-65 and Y-Wing
- Next year we get a 'Rebel Veterans' expansion, with that black/orange T-70 and an E-Wing. Maybe in that same black/orange scheme, because how cool would that be?