The CW is by far the smallest network, and Supernatural wasn’t even in the top three for highest-rated CW series in the 2015 – 2016 TV season.
The fans went into enough of a voting frenzy for the EW Fall TV Preview cover that Supernatural beat out sixty-three other series to take the top prize.
As long as Supernatural holds on to its incredibly loyal fanbase, it could definitely last to 300 episodes.
Supernatural doesn’t exactly have the highest ratings on network television.