This article is considers lots of approaches to solving a concurrency problem, but of particular interest are the sections showing the power of the Concurrency TS future.then extension and the coroutines proposal:

Modern Asynchronous Request/Reply with DDS-RPC

by Sumant Tambe

From the article:

A quick look into N4402 reveals that the await feature relies on composable futures, especially .then (serial composition) combinator. The compiler does all the magic of transforming the asynchronous code to a state machine that manages suspension and resumption automatically. It is a great example of how compiler and libraries can work together producing a beautiful symphony.

... Indeed, this is truly an exciting time to be a C++ programmer.