Es gibt sehr wohl den neuen Faktor @3x:
For iPhone 6 Plus:
1242 x 2208 (@3x) for portrait
2208 x 1242 (@3x) for landscape
https://developer.apple.com/LIBRARY/PRERELEASE/IOS/documentation/UserExperience/Conceptual/MobileHIG/LaunchImages.html
1242 x 2208 (@3x) for portrait
2208 x 1242 (@3x) for landscape
https://developer.apple.com/LIBRARY/PRERELEASE/IOS/documentation/UserExperience/Conceptual/MobileHIG/LaunchImages.html