Reports indicate that the next iteration of iOS may fix an exploit hole that's enabled the Evasi0n jailbreak to become particularly popular.
It's not as though jailbreaking as a pastime is likely to die off, but Forbes reports that Evasi0n's author, David Wang, has looked over the beta 2 code of iOS 6.1.3 and the news isn't good. A time zone exploit that Evasi0n uses has most definitely been patched, and Wang suspects others may have been as well.
"If one of the vulnerabilities doesn’t work, evasi0n doesn’t work. We could replace that part with a different vulnerability, but [Apple] will probably fix most if not all of the bugs we’ve used when 6.1.3 comes out."
Realistically, this won't change much. Jailbreaks come and go, and there's enough of a community already that it's likely that iOS 6.1.3 will be broken at some point. Still, if you're already in the jailbroken world, it's been wise to avoid new iOS updates anyway as they appear if you want to keep your jailbreak active, and this simply strengthens that argument.