At the very worst, if the professor misses the grade submission deadline, the registrar will put a 'Z' in the grade bracket meaning that the instructor failed to turn in a grade on time. I know this, because it happened to me with my American Gov. class, first semester my freshman year. However, my professor had an excuse: He had to go on medical leave and informed all of us that he was getting an extension for submitting the grades so we had all expected it. Nevertheless, it still affects your GPA, but only temporarily.
Should it happen to you, I would contact your professor as soon as possible to see when the grades will be in. If you're not getting a response soon enough, then contact Dean Lawler, or the registrar and let someone on the higher end of the ladder know what's going on.