To be honest ... all the things you mentioned like the Launcher, Payment System, Banners, Database, Steam are already there, most of it since (almost ;-)) day one! Do you have to code a new launcher or shop system for adding a new map or a new weapon? Surely not.
Fun fakt: We already had an update cycle of about 2-3 months for new stuff from Wiple. Was no magic back then. And yes, adding weapons /new skins /new maps IS almost a copy & paste job. We've seen that a thousand times for Events like Halloween, Xmas, Valentines, when games all around the world add new stuff like pumpkin helmets and weapons with Christmas tree lights ... no need for testing this for half a year. A new weapon? Add the 3D-model, animation, skin, sound and its database values ... done.
I made that myself for much more complex stuff like adding whole new custom Airplanes to a Flight Simulator game.
Unless Aeria is asking Wiple to make some really, really deep changes to how the game appears and works, all the statements for the huge delay are fairy tales ...