What constitutes hipster metal? The two seem diametrically opposed. Is it like Mastodon? If I stretch my imagination that is the closest I can come to envisioning such a concept.
it depends on what you mean by "hipster" & "metal".
More than a specific "hipster metal" I think people mean the hipness of certain kinds of metal, especially; drone/doom (esp. Sunn O))), Khanate & other O'Malley/Southern Lord stuff, also Boris), sludge (Electric Wizard & all that), some strands of black metal (i.e. bands like Wolves In the Throne Room or Xasthur getting reviews on Pitchfork). As well as metal & liking metal becoming "cool" over the last, say, 5-10 years. Also a hipster reappraisal of bands like Eyehategod, Sleep, Earth, as well as a lot of black metal.
The thing is, metal seems inherently "uncool" - that is, metalheads almost all are very sincere, very low irony quotient (which I'm sure is a major part of the appeal to hipsters), which I reckon kind of makes it immune to hype cycles. Like, metal dudes are making metal because they believe in metal. Rain or shine in they'll continue making metal.