Then, effort on making functionally orientated base libraries (without relying on baking those things in FSharp.Core, but as set of small libraries) wrapping undelrying .NET APIs, taking inspiration from what is there in Haskell and other similar languages.
Most F# users today are fine relying on mostly .NET libraries + fresher F# libraries, but most projects will be done with a mix of paradigms (which is manageable in F#) which is not most appealing to people with significant FP background.