Again, sharing my theories in an expansion specualtion thread:
I think the Prequel will be a new starer set, treated like World War 2 for Wings of War. The rules set will basically be the same but the prequel fighters may have new upgrade possibilitites, card art, and factions to make them stand apart from their Galactic Civil War counterparts. Players CAN play them against one another, but the factions would not be designed to cross-connect. I expect we wouldn't see such a thing until around wave 3-5 were being pushed.
I think the K-Wing is a wonderful idea of a ship and would be a nice heavy fighter altenrative to yet-another-corellian-smuggler. When folks suggest the YT-2400, I only wonder "How is this ship different from the YT-1300?" Both of them are correllian smuggler ships without much of a difference, to me, except cosmetics. The K-Wing makes more sense to me as the next rebel heavy ship because it would be distinct enough to play differently from the Falcon.
The B-Wing and TIE Bomber are both bombers but honestly I think the B-Wing and TIE Defender are better matched against one another as heavy fighters packing a ton of firepower. The Bomber's counterpart should have been the Y-Wing, but FFG Felt like flying the TIE Advanced instead, leaving the Bomber the odd fighter out it seems.
For the Bomber, now that I've seen the utility of the Slave I's bomb, I can see the TIE/sa having a bomb slot and two torpedo slots, making them cheap minelayers or torpedo delivery systems for the Empire. Presnetly the only torpedo user in the Imperial inventory is Slave I… and that's only the Slave I itself since the other firesprays only fire concussion missiles IIRC.
My personal wishlist covers the TIE Defender, Assault Gunboat, and R-41 starchaser. The latter two aren't typically represented in the star wars universe and it would be nice to see them included. I can think of many uses for the Assault Gunboat, one of which being a cheap platform to deploy Ion cannons for the Empire (instead of relying only on the Slave I).