Should it be core only or require one of the expansions? I have all the expansions, so I will be happy no matter what they choose to do,but am curious about what everyone else thinks. I thought Jabba's Realm was a good choice for the last campaign, it has a lot of good stuff in it and would be the first expansion I would recommend anyone to get. On the other hand, it might be better for FFG to release a second campaign based on the core box. That might convince people who have been considering buying the game primarily for the app to buy it, which is good for everyone.
If they were going to tie it to an expansion though I'd like to see it them use Heart of the Empire. While I would love a Hoth or Bespin campaign, I think after Jabba's Realm that Heart of the Empire is the best value as it has three good heroes, a great villain, some really good imperial groups, plus equipment and crate cards that are as good or better than either of the other two. Twin Shadows is too much like Jabba's Realm (and the weakest expansion in my opinion), and while Tyrants of Lothal is great, I think that the settings in the three I mentioned have significantly different locations, while the Lothal tiles are very close to the desert tiles which were all over Jabba's Realm.
With Hoth, Verna is great, but needs a lot of gear, MDH1-19 is a good support and Loku works for me as a hybrid sniper/support hero. The imperial and scum groups are not as good as Heart of the Empire's, but the equipment and crate cards are around the same level (MDH-19 gaining and givein artificial stimulants to a strain heavy hero is quite good). Sorin and Dengar are not draws in my opinion (I know there are people who do love Dengar, but I'm not one of them and have gotten along just fine without him. IG-88 or Bossk proxy for him on the board when he pops up.) I have mostly used Sorin as a proxy for named imperial officers. It also has Wampas, which I hate seeing spawn outside of snow tiles or missions where it would make some tort of thematic sense. I think he is much better in the app than the paper campaigns if I recall correctly. It would be the third expansion that I'd recommend people buy.
Bespin Gambit is the expansion that I am most tempted to leave out of my collection in the App at the moment. Murne is a good support, but Davith is one of the weaker heroes. Wing Guards are specifically Bespins security forces and I don't think that Ugnaughts should be in the game and they are not really very interesting (unlike say the Nexu, who I potentially would detest since are from what I consider the worst movie, but are different to other imperial groups and can be very useful for the imperial player). The equipment and crate cards are respectable though. Agent Blase the other villain that I have not bothered to get. Ironically he and Dengar have spawned for me the most along, with the Emperor in the app.
I suppose the other thing FFG might do would be tie it to the expansion that has sold the best. I would guess that Jabba's Realm would have been the best sellerout of the expansions, but I have no idea which one would be next.