During Morrison's Action Comics run the reader finaly learned if Superman had died in the new 52. Lois Lane remembering that day whispered to herself "Doomsday".All of the information came in an issue were the past, present and future had collided with each other. So there is a possibility superman hadn't died yet but he will.

We also know that Max Landis and Grek Pak would write a project about the death of Superman but it was cancelled. Finally Doomsday makes his first appearance in the new 52 in the pages of Superman/Wonder Woman.

Is there the possibility that Doomsday will kill Superman again?

No. If the events of Superman #75 - The Death of Superman! have already occurred in whatever continuity DC pretends to follow, then it will be suspenseful, but I think more likely that Landis and Pak will try the tactic one sees in Star Trek: Into Darkness, and WW will die. Then, after everyone goes apeshit, they'll relaunch her in a new series so that Wonder Woman will attract some buzz again for a few months until the writing slips back into mediocrity.

Landis has confirmed that he no longer works in that project due to his tight schedule.
We don't know how superman died so we can't confirm if Superman had the same death as in Superman 75

@squalleon:

Not long ago, you said goodbye to DC Comics. I did well before that. What has renewed your sense of optimism for this?

@riot_sqrrl: Well buying a title and discussing about it is different i still want to keep up with the news and discuss about the developments.

And this is a theory that was bothering me for days.

It was heavily implied (if not outright confirmed) back in Swamp Thing #1 that Superman has already died and resurrected.

This is a prime example of cluster@&ck editing. Writers wrote without having clear information themselves.

I think Morrison just wrote whatever he wanted to without caring what editorial said.