Are there any plans for a future C standard after C11?
I sent an email to the guy on the WG 14 contact section but I didn't expect to get an answer anytime soon, however, I did.
This is what he replied to me:
the Committee has not discussed starting work on a new revision of the Standard. WG 14 will be meeting in Parma Italy the first part of April, and so far there as not been any proposals for new features that would prompt the revision process.
Thanks,
John Benito - ISO/IEC JTC 1/SC 22/WG 14 Convener
So I guess this is as official as it gets for now.
There is C18 (https://www.iso.org/standard/74528.html) standard released in June 2018 but it only addressed flaws in C11 without introducing new language features.