Sure, there will be snafus. Some of them, especially those involving bureaucrats or financial institutions, will be a real pain to resolve. Of course, some computer somewhere will report your age as a negative number and deny your retirement benefits. Chances are you won't be the first one to call and point out the error. Chances are a person will know you're really 70 years old, not negative 30.
Chances are they'll be prepared to correct the error.
The hysteria has crossed the line from comical to annoying. It's also bringing on a little deja vu for me. Unlike the DataCrime 'fizzle' of 1989, which contained similar destructive capability but never spread, the Michelangelo appears to have become 'common' in just 10 months following detection. So, everybody worried, and everybody ran out and bought anti-virus software, and everybody sat on the edge of their chairs as March 6 approached. And March 6 passed without much excitement at all.