My two penn'orth is that, as far as I can tell, Beats are not being bought as "high sound quality" headphones, they are being sold as badge swank/costume jewellery. Gotta have that big dumb red 'b' on your lugs or you're not where it's at... as I believe the kids put it.
I reckon that the majority of Beats owners are pretty much unaware of the existence of Pono, HDTracks, FLAC, dedicated headphone amps or anything of the sort. Pono's Kickstarter success is big, but only by Kickstarter standards. the number of people who have backed it is in the tens on thousands, not the hundreds of thousands, let alone millions, which is the market area where the big boppers play.
Pono investors are (I hope!) the anti-herd, and people who, if they have decided to put down hard cash on a player than promises high quality replay, will be aware enough to buy headphones that will deliver exactly that.
I also seem to remember reading that the Pono website will be recommending headphones for Pono, rather than making their own. That keeps a currently buoyant market sector on their side, instead of alienating them by tying Pono users into a single-brand ecosystem. Smart. That's what Apple did, by supplying earphones in the box that only a tin-eared gadget journalist could love.
I hope. . .