Uh, no, not really. They are shipping 4 versions a year, so if they keep the current pace, we in fact won't see version 1243053 until the year 312774

Granted I hope we have transcended browsers by that point.

https://wiki.mozilla.org/Firefox/Roadmap

I think we'll see a phase out of version numbers on public facing download sites and just have "Firefox" instead of "Firefox v4, v5" etc. Internally, devs might have Firefox 1243053 but we might never see that as the version number, sadly.