You are correct that there is a big danger of a duopoly. The previously Microsoft-dominated world of computing was boring and in places stagnant. Repeating that hegemony would also be boring and stagnant.

That's one reason why I think viable ecosystems are valuable. The question is whether someone can stitch together a Tizen/Yahoo/OEM or Jolla/Baidu/OEM, etc. axis and make it work.