The only reason why his death was considered an "event" and so big/important in comics history was because Superman was well established to both readers and the fictional characters of the DC Universe.
He was loved and adored, for the most part, by the readers and characters within his world so when he kicked the bucket, it made an impact.
The impact wouldn't be near the same if he were to die at the end of this film.
I'm probably going to go with the notion that there's a chance that Superman may be presumed dead by some unknown event, possibly involving Batman, midway in the film, which is why only Bruce shows up to the SV Cemetery as a result of his guilt.
And that after the new threat emerges, Superman comes back to fight alongside Batman and Wonder Woman, which leads into the JL film. I mean if Wonder Woman had become allies with both Batman and Superman near the end, then it would make sense for Wonder Woman to show up at Clark's funeral in SV, but Gal was not spotted there at all
Now if Snyder is stupid enough to kill Superman at the very end of this film and allow the JL to be formed without him, then that doesn't bode well for the DCEU while it remains in his control.
He'd be a liar, a hypocrite, and a idiot for having gone about it that way.
So we'll have to wait and see.