Ok, so here's what I'm thinking. Instead of releasing content at all, it would be easier to just fire the entire development team and pretend like content is being made. The new SK calender is as follows:
--Year One--
Jan.= xmas event ends midway through
Feb.= Celebrate valentines day, add "new" costume = various pink/red/whiteish reskins of whatever
Mar.= Tortodrones + remove a random rarity/change some random piece of gear to be absurdly strong
Apr.= S3cr3t GM forum + Anniversary event
May.= Run black kats towards the end of the month
Jun.= Test the handguns again, pretend like you're giving them to us... but don't.
Jul.= Winterfest in july event! One week only!
Aug.=Run apocrea as a stand alone from halloween.
Sep.=Tortodrones again
Oct.= Octoberfest! Oh wait no wrong thing. Dark harvest... whatever that thing was.
Nov.= Thanks giving + flash sales
Dec.= Big hype for xmas event.
--Year Two-- (Same for all months not listed)
Jan.= xmas event ends midway through
Mar.= change the random piece of gear changed last month back to how it was. Open testing server for this.
May.= Tease at "new content" once again, and then act like it didn't happen.
Jun.= Biscotti will occasionally walk around for a week or two as if hinting at something.
Jun.= Invent a staff member and have an existing staff member "quit". For instance, Eurydice could take on a new name and pretend to leave.
Jul.= Black kats
Aug.=Tortodrones
Sep.=Surprise caketastrophe!
--Year Three--
Start over at Year one again.
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.
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So as you can see, there won't ever actually be any need for content, because the players that "stick around" will all be gone by the next year regardless of whether you're working on actually improving things, and a fresh batch of players will be there to go through the Calendar. I really think that this could save you guys a lot of time and effort trying to save a dying game, and would give you time to work on a project that actually deserves it.
You forgot the "Make whoever is the lead dev at the time quit their job" for January and the "Show secret forum and pretend it's not there despite how obvious it is" for April