Major characters in the Marvel Comics universe are going to be dying less often. Many characters have passed away in the Marvel Universe, but a number of those have been resurrected at some point, thus arguably diminishing its effect.
Death of major characters in comics has been happening for years. Some have been highly publicized. The Death of Superman and The Death of Captain America were both reported on by news organizations. In Cap's case, though this wasn't the first time he died, this was arguably the first time it felt real, and even permanent (at least for a bit). Since then, a number of other characters have died, but came back to life. Many readers have criticized Marvel for killing off characters, only to have them return later. In Civil War II, James Rhodes was killed by Thanos. But, just two years later, he was brought back. Loki seemingly died recently in War of the Realms, but apparently he's coming back in July.
During a Swedish convention (via ComicBook), Marvel Editor-in-Chief C.B. Cebulski commented on character deaths. According to him, character deaths are going to happen less often. If death does take place, it will have more of an impact.
"I don't want death to be used to boost sales or to use as a shock value so people go 'Oh my God, Johnny Storm is dead!' or 'Wolverine is dead!' knowing that they're going to be coming back. If we choose to do it now, we're going to add a little more weight and permanence to the situation."
Cebulski also described the process Marvel utilizes when choosing to kill off a character. Despite what readers may think, Cebulski says characters are not killed off just for shock value.
"There's a lot of debates that happen because if a writer suggests that we should kill a character, it always has to be story driven first. It can't just be for shock value and normally it's a discussion that we have between first the writer and the editor and then the writer and the editorial team, so the process of killing off a character really is a group decision, and it's made always with the best story in mind."
Marvel Comics (as well as DC) is in an interesting place when it comes to killing off major characters. Marvel Comics is ongoing; it is probably going to make stories for decades and decades more. Unlike a manga, or comic series like The Walking Dead, the stories of Peter Parker, Steve Rogers, and Logan are likely never really going to end. The characters are timeless icons in the comics; irreplaceable. Yes, you could replace them with different versions, and we've seen that happen in recent years. But, these iconic characters always find their way back.
Resurrections of dead characters have been effective in the past. Bucky Barnes being brought back as the Winter Soldier was controversial, but ended up being acclaimed. Over at DC, Jason Todd being resurrected as Red Hood led to one of the most memorable Batman storylines. But, resurrections like these have happened so often since then. Thus, many readers agree that they are no longer as effective. It will be interesting to see how Marvel Comics will handle character deaths going forward.