No it's not over. This is just the beginning.
This was more of an HBO deal than a 'box office' deal. Keep up.
HBO has needed SOMETHING BIG, ever since Game of Thrones ended.
The 2 highest grossing (superhero) movies that WB has ever made was.....
Aquaman & Dark Knight Rises, which each earned WB a little over
$1.1 Billion dollars apiece.
Now compare those numbers to Game of Thrones.
All 8 seasons of Game of Thrones had a total production budget of
$1.5 Billion, and the show earned HBO
over $3.1 Billion in subscription revenue alone.
That exactly why HBO helped "green light" this Snyder Cut.
Because HBO wants another big "tentpole property" to keep up with all the Disney+ profits coming from Marvel content.
So HBO is driving this ship now.

Not the box office.
They have all the money needed to fund the next 2 sequels, if they want it.
So it doesn't matter if you think 4 hours is too long for a theatrical release...
Just be sure to use that Pause Button when JL2 drops..... on HBO Max again.