Arcade's decided that it's time his uninvited tenents start paying rent, or kindly leave his property. Entering through a secret entrance elsewhere on Coney Island, Arcade takes over the control room and then, the rest of his Murderworld. The present Brotherhood members have to deal with their base turning on them, and reach the control room to deal with Arcade.
The attack would only affect BH members who're currently in Murderworld. The entire thing would be resolved in one thread, so it's pretty much a single-issue plot. It'd be dated after WWX, and before the Brotherhood migrates to Sanctuary.
they're about to have a major attack on sanctuary anyway. being so close to that point, wouldn't it be a bit redundant?
That hasn't been talked about or really planned out publicly in a long while, so it's easy to forget.
But yeah, not feelin' Arcade myself.