I think that the Go++ you search exists already: Rust.
(no offense, but Rust has everything you need plus what Go has already)
EDIT: Mea culpa, it used to have. (ref. http://stackoverflow.com/questions/29428318/why-did-rust-rem...)
Well, you can always build your own interfaces to achieve a similar result. But why do you need go-routines ?
By the way, at least, Rust tries to handle concurrency the most he can (by analyzing if data race can occur, at compile-time for example).
What do you need more ?
Anyway, like you've said, the ecosystem is still maturing. But the more people are interested in Rust, and the more libs we will have.