The original Macintosh was programmed in assembler. As was MS-DOS and Windows up to version 3.1 (perhaps even in important parts in Win95?). The big boom of computing and the GUI had already happened. In the late 80s Turbo Pascal was really popular: http://en.wikipedia.org/wiki/Pascal_(programming_language) http://en.wikipedia.org/wiki/Turbo_Pascal
For GUI programming there was (and is) the Pascal dialect Delphi: http://en.wikipedia.org/wiki/Embarcadero_Delphi
What would the world look like if C would have been never invented? I guess our browsers would simply be coded in Turbo Pascal dialect.
And Visual Basic is still huge (#12 on langpop.com). Also someone could reasonably argue that from the concept and ideas SmallTalk and Lisp were way more influential than C.
That said, I feel a bit dirty to make this argument. Dennis Ritchie should be praised for his accomplishments.