Michael!Dean will last 3 episodes tops. They'll come up with some Macguffin to de-angelize Dean, and it will never be mentioned again.
Cas will continue to be useless, especially now since Jack pretty much took over the clueless newby role on the show.
Lucifer will return.
The show will tell us how Mary is a great person who loves her sons while doing absolutely nothing to show us this. I figure she'll run off with Alt!Bobby at the worst possible time, leaving Sam and Dean in the lurch.
Michael will be gone and done by episode 2 or 3. More boring filler episodes with demons or ghosts or angels, no interesting monsters or creatures. More fun-for-the-actors type episodes like the western and noir episodes Someone will get separated from the flock and a lot of the season will be spent looking for them Mary and Bobby will be a thing Rowena will get killed a third time The angels will find a way to multiply and make more just before Heaven crashes. Wayward Sisters will be squared away with one episode and never mentioned again. Another backdoor pilot that doesn't go anywhere
What I'm hoping for The real Michael will finally be let out of the cage. More monsters. We haven't had any decent MotW episodes in a long time An actual compelling villain More Rowena, more witchy type stories. Max Banes to come back. Remember him? The resurrection of old characters. If Heaven does fall, I'd love for Bobby and Charlie to host both versions of their souls and ultimately have memories for both. It would be an interesting way to have them back.