Stormbirds indicates the initial offering will be some version of the Midway planeset. Jason also indicated it will be, initially, pared down somewhat.
So; Val, Kate, and Zero vs Wildcat, Devastator and Dauntless would be the most likely WAG. Follow-on's pretty clearly would be the A-26 and Catalina for the US. There are semi-historical peers for the Japanese side as follow-ons, think G3M and H6K, though they were not present for Midway. Otherwise it'd be probably be an E13 and some ear fluff if we are dead set on a true to Midway planeset.
I'd expect one or two fleet carriers, a destroyer, an oiler and/or cargo ship and maybe a submarine per side in the early offering. Also a WAG on my part.
The article said Midway Island will probably not be in it's most detailed state at release but I'd expect all of the AC and ships to be in their final form. I find the possible inclusion of the Hawaiian Islands to be necessary as it would give the online community a small map for PvP combat. The entire chain is big enough and has enough airfields to suffice on a small map. The historical significance of the air raid there cannot be overlooked, obviously. And it is, essentially, the same planeset as Midway with the potential for AAF additions.