Kiernan Shipka and Gavin Leatherwood dish exclusively to ET about Nick and Sabrina’s ‘happily ever after’ twist in the series finale. Plus, Shipka reveals how she really feels about never crossing over with ‘Riverdale’ and how that ‘Sabrina the Teenage Witch’ aunties cameo came to be! ‘Chilling Adventures of Sabrina’ Part 4 is streaming now on Netflix.