Superman: Man of Tomorrow will be the start of the new universe.
Obviously the upcoming animated film focuses on a younger Clark than we ever saw in these films and the one screenshot shows a new art style. As a result we assumed that the film was a standalone with no ties to these films.However at the end of this film Barry goes back in time, to create a new timeline, given that the present one was beyond saving.
Therefore it stands to reason that Man of Tomorrow will be the first film set in the new timeline, building from the ground up.
- Chris Palmer, the director of that movie, confirms that this is not the case.
The new universe that was created is the Arrowverse. While the DCAMU becoming a live action media might seem like a pretty huge jump, it should be noted that every time the Arrowverse is shown in an animated form they use the same art style as the DCAMU. The Arrowverse being the new universe would explain why Constantine and Ritchie Simpson look nearly identical as their animated counterparts.
- They could even use the reasoning that Pre-Reset Flash made sure that Darkseid never exists in this universe as the reason why the Arrowverse couldn't make him a threat in past and future crossover events.
Alternatively, the new universe created is the Young Justice universe. Comparing each universe, there some very common similarities between the characters and motivations, except this time, everyone has a happier ending. It's even possible that whatever void Darkseid and Trigon went into actually HELPED them and allowed them to be unaffected, prompting this weakened Darkseid to instead plan ahead, because his previous plans clearly failed and he doesn't wanna repeat that in this new universe. This could also explain why he visits Earth even before most of the heroes are even born and destroy the Earth before any of his old enemies come to be. It's just that we have Vandal Savage to thank for impressing Darkseid enough, he decided to spare Earth this time around. The heroes of either show's universes will never suffer a fate like like the ones in this movie...which is a sign that Barry's actions succeeded in making a brighter world.
Constantine Used a Compulsion Spell on Flash. When Flash asked for comfort when freed, Constantine obliged and also secretly put a Compulsion spell to as a "safety measure" having already been told about it by the Flash himself. He merely triggered it at the end of the movie.
The new universe will actually be the original universe pre-Flashpoint. Thus the DC Animated Movie Universe version of DC Rebirth. In turn rendering the entire DCAMU a Stealth Prequel.