well, I have absolutely no idea what Riemann hypothesis is, but apparently, if it is proved as true, then we can predict the pattern of prime numbers, of which number theory mostly consists of prime numbers
In science, when you get an answer, you get also several new questions. At the end of 19th century, physicists thought that Physics was nearly terminated. All the relevant questions had been yet studied and understood. It only left some "secondary" aspects that would be quickly dispatched... These secondary points gave birth to both Quantum and Relativistic Physics.. If Riemann's Hypothesis is confirmed, thousands of more interesting questions will arise. (And if it is refuted, then mathematicians will have a lot of work to do !!!) That's why science is so wonderful...