John would be just as distraught. We saw him always ride Dean hard in the series, but at the end he lets Dean know that he wanted both brothers to have the chance to live their lives in peace. Losing Dean like this, in a moment of self-sacrifice that he’d be driven to by his father’s words… John would have just as hard a time getting past that as he’d have getting past Sam’s loss.
Hearing that Dean was still alive… he might not pick up that phone, but he’d be in tears no matter what.
Brothers Apart 