.net core F# support has been pretty great from the initial stages of .net core from my basic usage. Biggest challenge seemed to be around type providers (F# system of generating strongly typed classes from dynamic data such as XML, CSVs, HTTP etc) but that's largely resolved. More info at https://github.com/fsprojects/FSharp.TypeProviders.SDK
There are some challenges coming up with design changes to the compiler and C# that might overlap what F# already has but it'll get sorted out.