http://www.ign.com/articles/2014/01/15/the-cw-president-on-how-much-longer-supernatural-can-go-and-the-status-of-the-spinoff

The last show left to originally air on The WB, Supernatural has had an impressively long life, and is now in Season 9. The show not only continues to be one of the strongest performers on The CW, but its ratings have been up this season from the previous year. Still, just how much longer could the series go?

Asked that question at the TCA (Television Critics Association) press tour today, CW's president, Mark Pedowitz, essentially said the show could go on indefinitely - as long as the ratings continue to hold up and the Supernatural team wants to continue.

Said Pedowitz, "As a fan of the show, who’s seen every episode, as long as I’m here and those numbers hold, God bless them. They can go as long as they want."

As for the potential Supernatural spinoff, which will be set up in a backdoor pilot this season, Pedowitz was asked if that was still in play and he replied, "Yes, very much so. It's set in Chicago. Hunters, monsters... The script just came in."

As for whether any of the main Supernatural characters would appear in the spinoff, which will be centered around new characters, Pedowitz said, "In the spinoff episode, they'd be in it. Whether they're in the series... For me, for spinoffs to work, you have to stand them on their own two legs, so you can only do those crossovers when the time is right, like we did with The Originals. We didn't see Michael Trevino's character, Tyler, until the seventh or eighth episode. By that time, the show was standing up on its own two legs."