I think people are reading too much into this. They cancelled Scooby Doo as well for the same reason. They didn’t see it making money given the scope of the movie and the marketing costs associated apparently. I don’t think it has anything to do with Flash or Keaton/Affleck, or the Coates movie. The Coates movie is probably looked at closer to The Joker as a prestige type movie. And I don’t think it has any connection to Superman & Lois’ future.
Like everything else, everyone is just finding some way to fit it into their priors.