It's about 99% sure now that the man is 'him', all that's left is his full unobstructed view of his appearance and the mention of his name. But I'm not here to fangasm about the ordeal (I am neither a hater nor a fan).
His return marks two key importance to us readers:
1) nothing is definitely definite even when it's obviously obvious unless it is conclusively conclusive
2) the "death" theme gets lesser and lesser meaningful
About the first point:
Mainly revolving around the deaths of the number of significant characters in the series. The key point here is "don't go and tag the character (as dead) unless you can clearly see the corpse". And the interpretation for "corpse" here is not just "a body" but "a DEAD body" at that.
p.s. The above is meant for blogs and people's thinking only, it does not apply to what should or should not be done over articles.
It further re-emphasised the fact that what may have been obviously a definite death in our assumptions does not and/or may not apply well in the OP universe. Two earlier examples of this are Pell and Bon-chan, and our 'man' in the recent chapter serves as the nail in the coffin on this matter.
You get a clear view of the corpse, in the case of WB and Ace, they are dead for sure and for good! You don't see a corpse, then regardless how obvious the way of killing or whoever said or hinted at the death, they may not be really dead. A good example for case study here is Monet's death by stab to the heart.
I think Oda played this really well as his trump card (or ace in his sleeves). He is famous for doing the unexpected, giving the least expected, out-of-box story for the enjoyment of his fans. He surprises / shocks you with appearance of "dead" person. He throws something into the storyline that you least expected. He makes characters do what you don't think they will normally do. He turns the story around 180 degrees when you are already confortable and expecting something to happen in the obvious direction it is taking. That is Oda!
About the second point:
I have stated this before in an earlier blog of mine, death does NOT serve a higher purpose in OP. We thought that by Sabo's death had catapulted Ace and Luffy to appreciate live and to life freely with no constrains as he (Sabo) died fighting for his own freedom. Well, his supposedly death DID do the job in inject the objective in his two brothers but what now...?
So what impact does that have on readers / fans? Less to none emotional attachment to secondary significant character (notice I say secondary). Example? Let's say Zoro vs Issho. Zoro could not fight up to the standards of the admiral. His swords were knocked away from his hands. As Issho about to lay the final decisive cut, Barty stepped in, took the cut and "died" on behalf of Zoro. Will you go through the shock of ["Oh no! Barty... Why must it be him?" *tears*]? I doubt it.
Or maybe Violet saved Sanji during his fight with someone of the Donquixote Family, but "died" in the process which caused Sanji to level up and thus defeated his foe. What are your feelings about this? Will you go "Poor Violet, her sacrifice gave Sanji the key to unleash his fullest potential" or will you do "Tch, don't worry, she ain't really dead. Sanji got (level up) it cheap (from a fake death)."
Free to discuss below.