It is GNU/Linux. Claiming that Linux is the most important part of the system is rewriting history (the GNU project started almost a decade before Linux was created).
There are many other kernels. Hurd is one of them. There's also several free BSD kernels (which were liberated around the same time as Linux was being made). And universities make operating system kernels all the time. Making a kernel is not as big of a deal as creating a fully compatible Unix-like operating system -- which is what the GNU project did.
So I don't agree that "GNU would've gone nowhere". If GNU had a kernel before Linus made Linux, then Linux would've gone nowhere.