My opinion is C and C++ need a divorce. So that C can be modernized with features that make sense in the context of the language. And not constrained as a broken subset of C++.
I think it's starting to happen because C++ has become so grossly Byzantine. C refuses to relinquish a bunch of niche applications. The heyday of OOP is past. 10 years ago the attitude was C is going to die any day now. Now it more like since C isn't dying it needs improvements. And none of them are backports from C++ nor make sense in C++.
C99 already isn't a subset of C++ (although I think it took until C++14 to finally give up on that), so any alignment is courtesy now, and it's recognized they'll deviate where necessary.
