Hopefully Mozilla can assert some control over when a carrier/manufacturer is allowed to call something "Firefox OS" (like they do with Firefox itself) so that there is a core brand which is un-crapware-ified.
Except mozilla has no real experience in marketing.
So you are hoping they can build a brand big enough and powerful enough that carriers are willing to cast aside their main goal of differentiation from each other, just so they can call their phone a "firefox os" phone, instead of hiding what it runs and calling it whatever they want.