When you think of it, because there are so many of the common german planes already in existence, it makes it hard to see how they would create what would be a "normal" planeset for something like Battle of Bagration. I wouldn't expect that to be coming for that reason. If they want to keep following their current battle model with planes from both sides, they're almost forced to go Pacific where there's a huge number of aircraft they can create.
What makes sense for collector's planes? B-25. It could be used here, in Russia, and in the Pacific. That's a win in so many ways. Plus everyone would buy it, and the exterior is being done already. Sure it would be complex but it makes sense. I'd like to see a B-26 but that seems too much work, though Jason pushed for it previously. German plane that makes sense is the A9. It was in BoBP, actually was flown, and they built about 1000 of them. The other types are rare unimportant types. Ar 234...I'm not sure what that would bring over what we have in a Me-262.
Spitfire XIV makes sense as well.
Looking glass says pacific soon™ as it's wide open for additional content. What would make a good first step would be New Guinea, not Midway. The somewhat Kuban like terrain with the Owen Stanley range, plus the fact that the fighting went on from 41 to nearly the end of the war, makes it great to be represented. Also, if you make the map big enough, it can cover the naval battle of the coral sea, which would allow you to use the USN aircraft from the early war. You could also ease your way into naval warfare and prototype stuff that you would need later.
I suspect they would still go midway first though.
Of course, they could just add in something that is missing from another pack from somewhere else, say a Yak-9T for kursk or a BF-110F for stalingrad, but that seems unlikely.