I think right now the problem is, the DCEU doesn't know how to move forward, if indeed it wants too. It probably thinks - do we need a shared universe, how would it be perceived if went seperate ways - damn you Marvel (i joke) when in reality... it should be so simple.
DCEU main players:
WW. No brainer.
Batman - if Affleck returned, people would still be excited.
Aquaman/shazam - some strong interest shown.
Superman, i have no idea - i believe if they put out MOS2 and it looked good, people would be keen.
Recasting - it may cause some to ask - why? maybe we delve in too deep about reactions etc and the GA probably don't care when all said and done.
Continuity - X Men has shown people don't really care much for it as long as they are entertained.
Casino Royal was a reboot, but kept Judi Dench as their M - it didn't stop the franchise success - same goes with Q etc before.
Ultimately, if the reviews and word of mouth are good, people will show up.
So the sensible option is to move forward, keep same cast and try to work out any continuity changes if the occur - such as if Amy doesn't come back, take out the character and bring another strong female character in and/or recast and make it work.
As it stands, we're all worried about movie forward after JL - the beauty of WW1984 is it's out of sync, in the time line it's already happened so it's its own beast. The follow up if there is one can follow on from (based in 1990's or early 2000's or way in the future as we have seen she doesn't age like us) that so the trilogy of WW solo's are their own things in their entirety and Superman can take a leaf out of it.
In theory BvS happened two years after MOS - decent writers can't sit down and place a MOS2 and MOS3 in that time period - off the top of my head (i actually love this idea and fan fic/day dream about it a lot) MOS2 is set months after MOS - metropolis is rebuilding, superman is showing washington he can be trusted, Swanick is keeping his word - they actually agree to do tests on superman - he races a jet, shows how fast he can manuever - he shows how far into space he can travel, he actually co operates with nasa acting as a shuttle for a space program. Natually the UN wont a meeting - we see Superman give a speech and hear their concerns and it's a real empowerment moment - we see what his deal is and we see the world accept it - let's move on. DP staff treat Clark as the new guy and he just goes about his business, the DP scenes focus heavily on Lois, Perry and the humour of clark laying low seeing everyone gush over Superman. We see the classic tropes, cat out of a tree, armed robbers, the final act and the pay off would be Lex Snr inviting Superman to intervene in politics - which he doesn't want to do - other countries get itchy fingers - tensions are high and devisive.
Lex snr sets off a missile from an unknown location at sea, as this time, governemnts all are confused as to who - america is ready to strike back and russia, nk are all ready - the DP, with lois have been tracking this and worked out it was him, but is it too late? Is WW3 imminent? he was wanting to stir the pot the whole time, now he is framing rogue nations, heading towards the states - superman has to get involved as lois and co work with Col Swannick to alert the nation. They watch as the radar shows the missile change course and up into space then nothing - from our end we see superman grab the missile and wrestle it away, avoiding air craft as he takes it up and out and then boom.
Back on the ground the lex corp offices stormed, lex is gone, however, superman is standing at the entrance to a bunker and is looking pissed - single handedly infiltrates and gets lex out to face justice.
After credits scene - a large, skull like asteroid is heading to earth - fast.