Mads Torgerson (the head of the Roslyn project; C#/VB Compiler) showed once a slide, that c# devs are counted in millions, VB devs in 100k steps and F# devs in 10k steps.
F# is a wonderful thing for the ecosystem, but practically of no importance regards priorities.
IMHO: To make UWP and F# a thing, UWP need to be remodeled to a primary react like system. That however will never be a story, considering the state driven UI development MS is doing for decades.