Frankly, Solomons or New Guinea as not the second installment is inconceivable (and I will be sorely disappointed if the appropriate meme is not immediately posted).
Midway has name recognition going for it, among the lesser versed in the aviation community, and therefore maximum sales opportunities. If you say "New Guinea" to the average MSFSimmer and probably many Air Quakers, it would not resonate. Midway has at least a pair of movies and one in the last five years that did well in theaters/streaming services. It is among the most famous battles of the war. I don't know about today's students but it got a couple of pages, as did D Day, in World History class back in high school. It is clearly the best choice to start the franchise development from both equipment and marketability standpoints.
Provided it sells well, you will get one or both of the aforementioned Areas of Operations. For me, I'd also like to see Hawaii/Pearl in the first iteration or Hawaii/Pearl and Coral Sea in an early add on. But that's just me and my wishful thinking.
Fett