Golang is pretty good, but you can't really count on gc and frankly goroutines are as much problem as solution. Nice to see a C with useful types and builtins.
Go has 25 keywords, C has 32; it's an easier language. Even without the garbage collection, Go's memory management is easier and safer (memory is automatically zeroed, no pointer arithmetic). Go's toolchain is portable and straightforward.
TL;DR it keeps having advantages over C even if you takeaway GC and goroutines.
Also go has a -lot- fewer sharp edges than C.
It's an (extremely) ambitious goal, and skepticism is warranted, but I think their desire for such a thing to exist does actually make sense.