With every announcement this film puts out, it's just more and more obvious this film is a nasty train wreck waiting to happen.
If they were smart, they would've made MOS a trilogy and perhaps introduce a Justice League hero/villian in it here and there. Not to mention put out a Wonder Woman film and a couple others before getting to a Justice League film.
After all, Marvel hit the jackpot with gradually introducing the main heroes with their own films to smoothly build into a big ensamble film like the Avengers. This is something you just can't rush.
But DC on the other hand. MOS - Introduce new Superman, BvS
oJ - Introduce a new Batman
and Alfred
and Lex
and Wonder Woman
and Cyborg
AND Aquaman. All of this will lead straight into the Justice League film which is being filmed back to back with BvS
oJ.
That is just too much to introduce in one film, and look as just some of the extra issues here with trying to force in the Justice League. If they really try to push the Justice League in this film, then it takes away the focus that this is "Batman vs Superman". However if they don't focus enough on the Justice League, then they got jack diddly going into the Justice League film right afterwards.
There's many other issues as well, but mainly there's a ton of directions this can screw up badly plot-wise alone, and the films are just not in the right hands.