For a while, it looked like the CW series Supernatural was going to run so long that it would be the horror equivalent to the Western show Gunsmoke, which ran for twenty seasons. Then it was decided that the show would be wrapping up with a twenty episode season 15 – a little short of Gunsmoke's run, but very impressive in its own right.
Now the fifteenth and final season is turning out to be more difficult to complete than expected, due to the production shutdown caused by the coronavirus pandemic. On March 23rd, the thirteenth episode of the season aired, and that's going to be the last one for a while. It's not yet known when the remaining episodes of the season will be airing.
Executive producer and co-showrunner Andrew Dabb took to Twitter to let viewers know,
We have filmed through episode 18, however our visual effects and sound departments have closed because of the outbreak. So, right now, the episodes can't be finished. However, have some special treats coming along the way — to help us all get through this.
So there are five episodes that have been filmed but can't be completed, and still two more episodes left to film. Thankfully, it doesn't sound like Supernatural is just going to be abandoned and left open-ended. Dabb assured everyone,
And yes, we, the CW, and Warner Bros fully intend to return and finish the series. It's not a matter of "if", it's a matter of "when."
Hopefully the "when" of things getting back to normal isn't too far away.