But I know a lot of people, including me, will be bummed that we might not be getting an actual sequel to MoS.
I'm not. I like Cavill as the character, but there's little about the specific MoS continuity that I'd want to see followed up on. Better to make a fresh start without the baggage, whether it's a new continuity or just a continuity-neutral story that's nominally set in the DCEU but doesn't dwell on past events (i.e. pretty much the way the DCEU has been working for the past few years).
I wonder if and how they will make an actual transition movie or scenes or if they will ignore the Snyderverse completely and just start over.
The best approach might be something like Marvel's
The Incredible Hulk, which just jumped right into a post-origin story in such a way that casual viewers could believe it was a sequel to Ang Lee's
Hulk even though it was actually a reboot. See also
Star Wars: The Clone Wars vis-a-vis the earlier
Clone Wars "microseries." It initially seemed like a continuation, because it picked up microseries characters like Asajj Ventress as if they were already established rather than giving them new origins, but it turned out to be a separate continuity.
First option would be to either make a complete transition reboot film aka the universe ends cataclysmically by known comic book means ( time travel, supervillain plans, anything else) and the result after a big event series in the comics is a completely new continuity. Comics have been doing it for decades now when the existing continuity was burdened down by too many issues or you devote part of the first new continuity film explaining the reboot somehow ( hard to do and not a very good option).
Please, no. The Arrowverse managed to pull that off in a messy way with
Crisis on Infinite Earths, but that would just make it repetitive for the movies to try it, and it would be way too cluttered a story to fit into just one movie. And it's just an unnecessary gimmick. Audiences have seen multiple different versions of Superman, Batman, etc. over the decades, and of other fictional franchises too. They don't need a new continuity "explained" in-story. Just tell a story about the characters, instead of getting all twee and metatextual and playing continuity games that get in the way.
The advantage is that you could retain some key actors because the audience can follow why and what happened.
As I said, there's absolutely no reason why the same actors couldn't play the same roles in two different continuities. It happens all the time. If audiences in the 1940s could "follow" Basil Rathbone & Nigel Bruce playing Sherlock Holmes & Dr. Watson in the present day fighting Nazis after having previously seen them in two Victorian-era movies, then audiences today should be able to "follow" an actor continuing a role in a new continuity.