G-man recently suggested (http://www.comicvine.com/news/off-my-mind-consequences-of-batman-incorporated-8/146132/) that Damian was truly dead and that even though we've seen him in the future in Batman #666. This doesn't sit right with me. We've seen how Grant Morrison deals with time travel before. He's not one of those people who is foolish enough to think that time travel can actually change things in the past. Think about The Return of Bruce Wayne. Nothing changed because Bruce got sent to the past. In fact, the argument could be made that he ensured his own future. We have seen a change in how Grant Morrison deals with time travel recently in Action Comics with the Legion saying "We have to save Superman, even if it means we never get formed". But that could be overly dramatic, or involve a tremendous amount of reality warping due to 5th dimensional influence. The Legion still manages to save Superman's ship and get him to Mars, both events which we saw in previous issues. So, I think it's fairly safe to say that the 666 future is still going to happen, or is at least a possibility.
Also, why would Grant Morrison announce the death two days before? Yes there was speculation that Damian would die on this very site. Yes, the cover of Batman, Inc. #8 made it painfully obvious what would happen. There could have been an announcement that "no one is safe" in Batman, Inc. vol. 2. There could have even been a hint that there would be another death after Knight was killed. And the RIP cover could have always been turned into a variant. Why use a direct spoiler like that to create a lot of hype?
My thought is that one of two things could happen. In the 666 future, we know that Damian makes a deal with the devil. He could do that now. It seems like there were certain events (Bruce's future death) that lead to that happening, so that might not be what happens. It is also possible that some idiot (maybe even Bruce himself. Tailia even) puts him in a Lazarus Pit, which makes sense given his family history. The point is, Grant Morrison could be setting us up for something really crazy with Damian. It could even be that the blatant spoiler in the NY Post was meant to attract more readers in order that more people might be interested in what lies ahead.
I don't think this is merely the end for Damian. I also don't think he will have a cheap return. I think Grant Morrison has had something planed for Damian's return since day 1. But only time will tell.