"First there was HipHop, the PHP interpreter which improved performance, now usually referred to by the less embarrassing name HHVM. Building on HHVM, they've just introduced Hack, which 'reconciles the fast development cycle of PHP with the discipline provided by static typing, while adding many features commonly found in other modern programming languages.'
Over the past year, Facebook has converted nearly all of its PHP code base to Hack, which makes up the core of its website."
If Linus is content with C, I think he's right. To me, it's the only nearly perfect language, as judged by how well it does what it's trying to do. In other words, there isn't anything substantial that can be improved in C without it becoming a different language.
Other languages certainly have their purpose and place because they try to do different things. For example, Python is extremely good at what it does. But no language can ever be better at doing C stuff than C itself. Compare that to C++, which has its merits, but is far from perfect in terms of how well it does what it's trying to do.
In other words, there isn't anything substantial that can be improved in C without it becoming a different language.
A native string type would be nice. I love C, I enjoyed learning it, but I was astounded by the gyrations (library functions, etc.) you have to go to to use strings compared to the BASIC I had previously learned. C's unfriendliness to text manipulation is one of the reasons I switched to Perl when I got into CGI Web programming in 2000.