If "Epicenter" is referring to anything in particular, which it quite possibly isn't, I would guess that it could be referring to a new Apple TV[1] being announced that will serve as a hub (i.e. the device in the center) for HomeKit.
[1] Could also be an updated Airport but Apple TV is more likely as 1. it makes more sense overall and 2. it is very likely there will be an update (Apple website currently says that it starts at $69 but there are no other models / configurations).