Saving people, hunting things, the family business. 👨👩👦👦 #Supernatural is celebrating its 300th episode with an epic Winchester family reunion! See our exclusive report from the @cw_spn set for all the details: https://t.co/70Dq9ROm7u pic.twitter.com/AaS5YGi86S— Entertainment Weekly (@EW) January 16, 2019
JDM, Samantha Smith, Jared, Jensen, and Misha all have EW covers to celebrate SPN's 300th episode, which airs February 7th.
They won't reveal exactly how John (briefly) comes back (along with Kurt Fuller's Zachariah) but he'll reunite with Sam, Dean, and Mary, sharing a beer with his sons.
Sources 1, 2, 3