The major benchmark for browsers has been Internet Explorer, which has had 9 versions in 16 years. Compare that to Google Chrome, which is already on 14.0.803.0 (dev) / 13.0.782.32 (beta) / 12.0.742.100 (stable) after existing for less than three years. Mozilla is moving away from Microsoft's release model and towards Google's release model. While the current timeline for Firefox is a major release every three months, the target timeline is for a major release every six weeks.

Technology gets faster. Version numbers are arbitrary. Mozilla will be fine.