I personally think Kakashi's generation is going to be skipped when it comes to the Hokage question. Otherwise Kakashi would be the obvious choice. I think Tsunade will hold onto the position until Naruto matures enough to surpass everyone else and is the obvious choice.

Shikimaru is definately a good choice right now, but I agree with others that he doesn't have enough techniques and skills powerful enough to be anymore then great support without having prior knowledge of his opponents.

As for Sakura, she definately holds the potential to become Hokage. She is more passionate then Tsunade is, and is arguably just as strong as Tsunade now. Tsunade only surpasses Sakura in the form of her Slug summoning, and knowing more techniques due to time and experience.

In my mind at current, I'd say Neji is the best candidate. He has the smarts, and has the ability to counter most attacks. He'd need to gain a considerable amount of chakra as he continues to grow though.

I don't want to limit any ages when talking about Hokages. Those of you talking about age limits are thinking real world applications, which definately make sense, but in this world with incredible strength, powers/abilities where kids can be uncharacteristicly mature, and powerful at young ages, I think it'd be based far more on the individual's statistics. Just look at Gaara. Noone in sand could touch him by age 6?

Now when thinking about characters maturing further and getting stronger, without a doubt Naruto becomes the only choice... He's already stronger then any of the others, and Kakashi thinks Naruto has even surpassed him. He's only going to get stronger and more deadly as he matures and gains more control over the emence power he already has.

My vision of a Hokage is someone who's specifically selected to guide the direction of and protect the village. Naruto has more love for Kanoha then anyone, and he's already one of the strongest Aces when it comes to protecting the village. When the time comes I just don't see anyone currently in the village able to come anywhere near the level that Naruto will eventually attain. My guess is without a doubt, Naruto will be the next Hokage...