Is there any meaning behind it? i think its just sending the "no one is safe" message.
I do think that's what it is, which is kind of funny. When they released that poster of Jon and the first Season 6 teaser featured old footage of him, there were a lot of people applauding HBO for coming clean on his resurrection and no longer treating the audience like they're stupid after all the "dead is dead" nonsense and the set leaks. I remember reading articles saying stuff like "finally HBO is letting people focus not on the obivous question of if he's coming back, but the far more intriguing question of what that means his storyline is going to be this year?".
But I actually think it could be the opposite and they're still going with it... obviously, the poster itself is supposed to be an ambiguous shot with you not being able to tell if it means Jon is living or if it's just a reminder he died, unfortunately I think that was to stir the debate even further rather than put an end to discussion. As far as the first teaser, the first shot focuses on Jon while Bloodraven's monologue tells you "the past is already written, the ink is dry" and then it cycles through shots of all the horrible things that happened in earlier seasons to characters that were irreversible then ending with a line from Bran saying "they have no idea what's going to happen."
Often the argument from the actors when they're told to lie to reporters about Jon's status boils down to "Remember what happened to Robb, remember what happened to Ned? Oberyn? Ygritte? This is Game of Thrones. People tune in for the surprise shocks and deaths, the fact no one is safe. Dead is dead, Jon got stabbed and none of the main character we killed off came back to life on the show before, don't assume you know anything." I think the promotional strategy is the same thing, they're basically saying with these promos "Oh, you smug fans. We're beyond the novels now, don't assume we're lying to you or that somehow you know better than us about what's going to happen. Remember all the doom and gloom from previous years? Things are gonna get worse, not better. Be very afraid, because that's what makes the show exciting.. right? There's no hope." .
It's a boring and tired message if you ask me. There's a limit to everything, you can only stretch the "no hope" thing for so long until it produces a boring story. I'd argue until the final season with the battle with the Others when all bets are off there are at least a handful of characters who are actually VERY safe and will continue to be so. Daenerys and Tyrion are two of them, it's laughable to suggest that either of them will kick the bucket when she's had a storyline disconnected from Westeros for 6 years now and we still haven't gotten the payoff for it. They're just gonna waste six years of audience investment in her character for shock value? Very unlikely. Every major character who died and we weren't expecting to die was actually done so in order to facilitate a bigger story George was planning: Ned was to kickstart the War of the Five Kings, the Red Wedding for the "North Remembers" subplot, Oberyn for the Dornish to enter the war, Jon for his resurrection/parentage discovery/probably being freed from his oath so he can go south.
Of course, there will be deaths just like every year, but I doubt very much we're gonna get the whole Ned/Robb/Cat & Jon (albeit temporary) kind of death happening again for a good while. There are some characters you just can't get rid of permanently without wrecking the entire story and making it a directionless mess. There are other characters who will die that we're still emotionally invested in, but ultimately they're expendable in comparison... or at least David and Dan view them as such. See the almost pointless deaths of characters like Mance and Barristan on the show. You can expect more of that kind of thing for certain.