Speculation on what the new superweapon and/or super fighter will be?
Another superweapon originally built to target Ulysses. As for the wunderwaffe plane, my money's on it having some sort of directed energy weapon or being a drone carrier like Nosferatu, or even the Nosferatu itself after AC7 brought back the Wyvern. I could see the cash-strapped Stovies licensing out the design, since we've seen the Alicorn go from being a Yuktobanian sub to one bought by Erusea.
In the Wyvern's case, it didn't have a prominent enemy character flying it until AC7, which opens the door for another potential returnee, the ASF-X Shinden from Assault Horizon. It's only shown up as a DLC plane and has no connections to a particular Strangereal nation otherwise.
Notably, all three planes are
also carrier aircraft so there's a good chance they return in AC8 as DLC or bonus unlockables, if not in the story, but I might just be limiting myself by focusing on carrier jets since it's expected that we won't be on the carrier for all of the game.
edit:
New interview with GameSpot was published.
Kono mentions that with the extended focus on clouds, they're going to play more of a gameplay role than they did in 7 where it was just a neat trick to dodge missiles or a one-off gimmick like with lightning.
There may be sequences in the game where you'll have to follow an enemy jet's wingtip vortices through the clouds to hunt it down (4:03) and clouds are going to present an obstacle where you decide whether to fly through it or go around it (presumably exposing yourself).