@UsoppSpell:
a chapter title. This is in no way similar to Pell. This is confirmed death on panel.
Besides, at the time that Coby felt the voice dissappear Ace was already completely dead, for even longer than WB.
Lastly, his VIVRE CARD BURNED OUT. A measure of a mans life force dissappeared completely, so yeah Im pretty sure its unreasonable to say that he can be brought back in any way short of magical deus ex machina that Oda is completely against.
Before I say anything, I'd like to remind you that I didn't say Ace is definitely alive or anything, I am simply saying it's a possibility. So with that established…
Shounen chapter titles troll all the time. DBZ would often have titles about character's dying or being defeated when that ended up not being the case. That said, I do agree that when someone "died" before in One Piece, the chapter title didn't actually say they were dead. It's just not such a ridiculous claim to say that maybe this is just Oda using a dramatic chapter title to really strike the reader since that's a common trope in shounen.
The fact is, lots of people have seemingly died - suffering attacks that would easily kill someone - and then have been treated as dead for many chapters before magically being OK with no explanation. Pell is one such example, Igaram another. Hell, even the little boy that some Baroque Works agents tried to kill to silence him was fine and dandy in the end, turning up with Igaram.
If you want to talk about what Oda is against, he also said he's against doing anything that will ruin the ability to have a party at the end of an arc, such as killing a character. Again, I'm not saying he won't kill a character but just that if you're going to take into account things he's said in the past, you can't just cherry pick the ones that suit your point.
Also, he doesn't like deus ex machina? So Shanks appearing out of thin air, right in front of Akainu just in time to save Coby isn't deus ex machina? Pell somehow surviving being right next to a bomb that was meant to destroy an entire city, with no explanation given? There are lots of examples of things just suddenly working out with no real logic behind it (usually characters surviving obviously fatal attacks with no explanation and then turning up at a really relevant time).