I have a controversial topic of my house to bring to the table. My dad and I made a bet at the end of season 12 regarding the death of Castiel. At the time we made the bet, Jared had already accidentally revealed the return of Misha. I bet that Jack would save Cas, and I think I’m right. As far as we know, no angel has ever woken up from “the empty”, and I believe that the only reason Cas was awakened was because of Jack. I would love to know your thoughts. Thanks!
Jack's powers are pretty much tied to his emotions at the moment and when he called for Castiel his emotions were in a turmoil. So, I think you are right. Cas would not have woken up without his help. Everyone who are tossed there have eternal "Empty" sleep.