Actually, if you watch anything on the CW it's coming back next season since they renewed all eleven shows!
I hear Supernatural stars Jared Padalecki and Jensen Ackles already had a deal in place that covers Season 12 and 13. The CW president Mark Pedowitz, a big fan of the show, had said repeatedly that the long-running series would continue for as long as the two stars want to do it.
Hey, if Crazy Ex Girlfriend can get a season 2 with the ratings it's been getting, if Jared and Jensen are signed through season 13, then I expect a season 13. Congratulations Supernatural and all the other CW shows!
UPDATED: Here's something in Variety's press release that just blew our minds!
""Supernatural,' which began on The WB in 2005, will be back for its 12th season, which will include the drama's 250th episode."
Story updated here.