I wouldn't bet on it. I have looked at a version of Gaia (Firefox OS's user interface and set of built-in apps) and the apps do not use any specific framework.
While a specific framework enforcing consistency might eventually appear, I do not think that this is the purpose of Mozilla or Firefox OS itself. Probably more the purpose of the companion marketplace.
This is the biggest challenge of building an html5 ecosystem: it is competing with high level, well designed UI abstractions. Help us solve this problem! Mozilla is focusing on the Web Components spec to try and offer a solution https://github.com/mozilla/x-tag
While a specific framework enforcing consistency might eventually appear, I do not think that this is the purpose of Mozilla or Firefox OS itself. Probably more the purpose of the companion marketplace.