The author of this blog post is a big fan of F#. While the language is gaining a lot of traction and showing momentum, the author argues that it is not yet mainstream by his definition. He uses the marketing concept of crossing the chasm to illustrate that while F# has many early adopters and supporters, it has not yet spread to the pragmatist and conservative users who make up the definition of mainstream. Pragmatists prefer to use what everyone else is using, even if it is predictably disappointing, rather than risking trying something unproven. The author argues that finding pragmatists in pain who are dissatisfied with current technology is the key to getting F# to cross the chasm and become mainstream.
https://ericsink.com/entries/fsharp_chasm.html