So there's the thickening plot. Joyce is convinced her son can be reached through living room walls, with a little help from The Clash. Eleven's nosebleed-induced powers find Will's voice over a radio frequency. Nancy has become obsessed with Barb's disappearance and will do anything to find her, even if it means going behind Steve's back to spend time with the creepy Jonathan Byers.
So basically no one knows if the two are alive or not. Even Hopper sticks his neck out in order to gather some truth from the shady circumstances pertaining to the discovery of Will's body in the quarry.
The mystery is well-mounted, utilizing darkroom photos, radio waves, and Christmas lights to paint a threatening picture of an outer dimension that may or may not be withholding Barb and Will.