I think a big appeal is having a second vendor to keep the market leader honest.
Google selling their own hardware and trying to stiffen requirements on Android devices are probably making most vendors feel a little nervous. Not necessarily that they'll be driven out of the market, but more that it will be ever harder to differentiate via software. App developers are clearly champing at the 30% tax bit.
So I'd expect the push to come from manufacturers and devs first, dragging consumers along. They might pick niches like low-cost devices where it's "this or a flip phone", like when the cheap Lumias outsold the entire rest of the Windows Phone market.
Comparable would be Samsung's tail-chasing with Tizen and Huwaei's forced embrace of its own OS.
If your selling points are “it’s all web apps and open source, isn’t that great!”, that is a…marketing challenge, to be sure.