User blog comment:The big croc/straw hats haki/@comment-3242083-20101213025726

Well, i guess they will develop some sort of haki, at least Zoro and Sanji (they kinda need to since the enemies in the new world are no weaklings). Also its not a big deal anyway, every vice admiral uses a variation of haki, so its not like giving them devil fruit powers.

My guess:

Zoro: Busōshoku Haki (Type 2, using it to increase his sword damage and cut logias)

Sanji: Busōshoku Haki (Type 1, using it to further harden/armor his legs for more damage and defense)

Nami: Kenbunshoku Haki / Mantra

Nami always seemed kinda special to me, in regards to higher senses. A lot of villains tried to steal her from the strawhats because of her great navigation skills. When she is asked why she "knows" that the weather will change, she just replies "i just feel it"

For the rest, Franky doesn't really need it, his gadgets can make up for alot, same goes for usopp and is pop greens. Chopper can enhance is df powers and brook might have a few new songs. I imagine him a bit like miss golden week, no devil fruit power but able to influence people.