Honest question. You keep expecting all of these to be readily available for you in C (as part of the standard). Why don't you, instead, just a use a language/ecosystem which already offers all (or most) of these for you today? (ie. D/Go/Rust/Nim)

> "* Reference counted allocator (basically, get libtalloc and roll it in [1])"

Why and how should that be standardised exactly? Memory allocation is platform-dependent, hardware-dependent and generally case-specific. malloc() and free() are the lowest common denominators the standard can assume, anything beyond that is simply restrictive. If you need a "reference counted allocator", why not just find/implement one that simply suits your needs?

> "* Coroutine standardisation would be awesome (stack swap primitives, with boundary checks etc)...."

Again, what makes you think this can be standardised across the infinite span of platforms and compilation-targets, where C is often used?

> "* In fact I want SIMD. I don't need these complex types."

I'm not following your point. You're simply asking for a better abstraction for SIMD. Also, as I'm sure you're well aware, SIMD is not available everywhere. Wherever available, you have clear instruction-set APIs/ABIs you need to follow to make it work. What else is missing?