Na, I'd say 6 dimensions is more of a reference to six paths if anything, not elements... but perhaps both. One is Deva realm, then Asura realm, Human realm, Animal realm, Preta realm, Naraka realm.
But then again, what do those dimensions' natures have to do with the paths?
Also a good possibility, although Six Paths seem to be more or less 'equal', not 'five with the sixth standing out'... And what about Gedo dimension then? But i really like the idea of the reference it would make to the 'Six Planes of Existence' of Samsara in Buddhism! According to belief, there are fiery and icy realms of Naraka, also a deserted wasteland would fit Preta (no food, not getting what you want)... Maybe there will be a forest world for Animal realm, a paradise-like landscape for Deva and a 'normal' one for Human...
We'd have the human world if the earth was a dimension, too.
Deva and Asura realms are one and the same, likely some prosperous environment like forests and cities. We may be yet to see it. Preta realm may be the desert Sasuke is in. Naraka realm may be both the lava and ice worlds. The place which connect all of them may be Outer Realm. Animal and Human realm may the world Naruto series takes place in.
Reason: mythology.
Volcano and Ice both being Naraka could also explain how she could warp everyone from lava to ice without using those portals, she only needs portals when going to an entirely different realm, not when moving people inside one dimension/ changing the setting of Hell from hot to cold
Yes, same dimension, different places.
Also this may be stretch, but we might have already seen the Deva and Asura dimension:
The only flaw to that is that she got them to the lava realm using "dimension shifting" and not "space-time portal" so shrugs.
Well, at least on that picture there's also a castle like in Naraka worlds ;) Though it might be stretch i do like this idea! Alternatively i could imagine the Asura/Deva realm as some kind of modern/technological civilization, which would tie in with Asura path being a cyborg. Remember that one color Cover with Naruto, Gamabunta and Sasuke as Mechas/robots not that long before the medieval/fantasy cover? It may not actually be related to this, but it could possibly show that Kishi thinks about adding some more technology stuff...