I feel like the show is getting a lot of hints that Soos might die later in the series. The video game foreshadowed it, Bill Cipher (the near omnipotent dream demon) mentioned it and it seems like Soos has an unusual number of near-death experiences… If the Pines family were ever in danger, I could see Soos dying to protect them. Soos is the type of person to sacrifice everything if it meant protecting the people he cares about and the Pines definitely fall under that category.
I love how the more disturbing moments in Gravity Falls involve a twisted version of Dipper and his reflection. It really does speak of how the biggest fears one can have usually have to do with oneself. I don’t think Dipper’s the only one whose afraid of being frozen in place, to never grow as a person or strive to be something more. Or even worse, watching yourself become a twisted, distorted version of the person you used to be. To look into the mirror one day and realize you don’t recognize the stranger staring back at you.