Akatsuki, Shiratsuyu, Akizuki, and Yugumo will soon(?) be coming to the tech tree, hopefully within the next few patches. They’ll no doubt arrive after the British cruiser line, and maybe if we’re lucky they’ll be here in time for Ranked Battles. I doubt they would be released during the upcoming Ranked season, so if they’re not out before then, I’m guessing they will come out in December, with the German destroyers shortly afterwards in January 2017.
I’m looking forward to them, especially Akizuki!