That said, it’s entirely possibly (and arguably even probable) that the Chilling Adventures crossover with Riverdale would have involved an alternate version of Riverdale not bound by the canon or characters of the CW show.
Earlier this year, the topic of Chilling Adventures of Sabrina crossing over with Riverdale came up with Riverdale’s Camila Mendes sharing her thoughts on the matter.
Based on Roberto Aguirre-Sacasa’s tweet, it seems a crossover would have finally happened in Season 5, which is no longer an option.