User blog comment:AYET/Perona's Negative Ghosts vs Shanks' Haki/@comment-3242083-20120205142657

It has been stated that Usopp is the only person able to withstand the effects of the Horo Horo no Mi.

The other character who was able to counter the negative hollows (Kuma) possessed a super hax fruit ability himself: the ability to repel EVERYTHING. So yes, the hollows would work on Shanks and every other extreme haki user, unless stated otherwise in the future.

This is actually what I love about One Piece superpowers - the characters wielding them decide how strong they are and what they do with them:

Perona could, in theory, dominate almost everyone with her DF - but she doesn't because she is a naive little girl with more or less humble desires (having a few underlings and living at a gloomy place - not world domination).

Kuma has the ability to send people wherever he wants to, coupled with the ability to reflect everything he wants. What's the twist here? Since be became a mindless cyborg he only uses his straight forward attacks like Ursus Shock and Pad Canon, instead of sending half of Whitebeards crew into a volcano or the deep blue sea. Oda didn't nerf the overpowered fruit, he nerfed the user. Simply brilliant.

On the other hand we have ridiculous Devil Fruits with no real power, like the Inu Inu no Mi, Model: Dachshund. I mean, wtf are you going to do as a Dachshund? But coupled with a competent user ( in this case a gun) it turns into a destructive weapon able to blow up a huge area.

Whatever, to sum it up:

1) The ghosts are intangible and can go through solid matter. If haki creates, literally, an invisible solid armor than it would be of no use. Haki is only known to have an effect on DF's when it is used for attacks - namely forcing Logias back into solidity or hurting "all-time paramecias" like Luffy.

While Shanks probably used haki to defend himself against Akainu's magma, it doesn't really compare to Perona's intangible ghosts.

2) It would, with the information we have at the moment.