It looks like this has died before its even been given a proper life http://www.theregister.co.uk/2014/03/15/metro_firefox_canceled/
Mozilla has bad news for Firefox users who are fans of Windows 8 and its new, touch-centric UI – all 1,000 of you, worldwide.
On Friday, Firefox VP Johnathan Nightingale revealed that he had made the decision to "take the Windows Metro version of Firefox off the trains" – Mozilla-speak meaning he's canceled it.
Mozilla has been working on a version of its browser that conforms with the UI requirements of Windows 8's Start Screen since 2012, before Microsoft's latest OS had even gone on sale to the public. But the effort has been a fraught one, with development delays causing its ship date to slip repeatedly.
A big part of the problem, it seems, is that there simply wasn't enough demand to justify the effort. As an open source project, Firefox relies on eager volunteers to test the prerelease versions of its code, but not enough were available for the Windows 8 version.
I suspect with the increase in lock in technologies being sought out by operating system manufacturers this sort of event can only increase in frequency.