Mmmh, given that the ninja's "prime" is said to be when they are around Kakashi and Itachi's age, a time jump would make some stronger and some weaker, while the genin need at least five or six years to reach Itachi-like levels (if they were to aquire such kick-ass power, which some would, definitely).

So say Kishimoto actually does a five year time jump, making the genin around 17/18... besides the raging hormones in the air, nothing would change much. Itachi would be in his prime, while Jiraiya, Tsunade and Oro would lose some power and Kakashi... well, I don't think he'd change much in five years.

The reasons I don't think there'll be a time jump is basically that the Akatsuki wont wait for Naruto to get stronger before taking him and getting the Kyubi for themselves. It'd be downright idiotic - "Oh, I know, let's wait a few years so that the brat trains under one of the Legendary Sannin, so he can actually fight back when we try to capture him!!"

So no time jump, I think.

On the other hand, if it happens, I'll console myself with the fact that hormones will rule over rational thought. Wheeee!