I worry about that too. In addition, I haven't seen any confidence that HKT can be implemented in a backwards compatible way, and that is one of the most-requested features (along with Async IO). I would hate to have to wait around for a 2.0 for this stuff.
The team has actually been pretty careful to design in a HKT-compatible way. While there isn't a fully-fleshed out design yet for Rust, there are designs in other languages, and we've looked at their pitfalls to make sure we can avoid them.
