SPN is their most popular show and with a steady rating.
The leads are very humble and unassuming.They didn't expect to go farther than 2-3 seasons.The cast and crew people are very tight knit and close after 10 years of always being together for 9 months out of 12 straight and there are a lot of people who depend on Jensen and Jared for a steady job since Hollywood is a hard place for that.
While they are still on air, many hit shows came and went during the last 10 years but SPN is still here.
And CW higher ups have given SPN greenlight and made it clear that the show will keep going if Jensen and Jared want to keep doing it. When they are done, the show will be done too.
Now their children are growing up and they are very committed to being parents, so SPN is on its end stages. Both Jensen and Jared moved to Austin and have homes very close to each other and are planning to open a winery business together , and their kids are growing up together. and they miss home, familyand their kids.11 season is either last or one of the last seasons I would assume.