Well, the current status quo has already confused a user (see msg286011)

> (so that people don't write code that expects them to be not coroutines in 3.6)

Even if people expect these methods to be coroutines, two functions of the asyncio public API (iscoroutinefunction() and iscoroutine()) disagree with them as described in msg286011.

In similar scenarios, we've always keep the code as is and clarified the docs in stable releases, then changed the code behave as documented in master.