We're working on Type Classes. It seems like HKTs (or anything like them) are going to be hard without diverging in a huge way from the rest of the .NET ecosystem.
That's fantastic news! I currently use Scala for most of my personal development, but having type classes would make F# attractive enough for me to switch over. I much prefer the cleaner syntax of F#.
Losing HKT would be a shame, but that's a trade-off I would be willing to make.
Scala has never properly supported HKTs though. When I last tried it, there were multiple open issues, e.g. the partial application of type parameters. So I really don't buy the argument that Scala scores a point over F# due to HKTs. If you want HKTs, use Haskell.
It scores at least 0.7 points though. That said, it loses points elsewhere (as do all languages).
I really think Type Classes will address 90% of what people want without requiring deep hackery. The solutions we have with class dispatch right now are workable but awkward.