The only comforting thing in all this is that in comics death is cheap. Damien will be back, it might be a while ( my guess is 2-3 years ) but he'll be back none the less. I mean look at his older brother. Jason was literally part of the the Bucky clause, the comic book exception the death is cheap rule, and he came back! So personally I'm just thinking of Damien sunning himself on some tropical beach vacation, drinking a soda while he waits for his contract to get renewed rather than thinking of him being physically dead.
Well, you were right. Damian's coming back. At least, there's an effort being made to bring him back. DC has a great opportunity to make a very great story here and have Bruce fail to resurrect his son. But, they probably won't.