It's nice to have competition in the marketplace; I don't think things would be nearly as good with just HTC or Oculus.
However the Rift and Vive are not perfect substitutes. The Vive Lighthouse system is fantastic for room-scale, but (relatively speaking) a pain in the ass to install if all you want to do is sit in a chair. And the lenses HTC uses induce a lot of chromatic aberration, which really does a number on text. So having either the Rift or the Vive pulled off the market would be a notable loss.