If Naruto looses the Kyuubi, I'm sure Kishi will find some whay for Naruto to survive it. I'd like it if Naruto got the Flying Thunder God Technique as "that jutsu" to replace the Kyuubi's speed. Naruto already has a HUGE pool of natural stamina and chakra (his not the Kyuubi's) but he could barely focus it in the beginning because the Kyuubi interfered greatly with Naruto chaneling his own chakra. Unless Naruto went berserk, and before he mastered the Kyuubi's chakra for himself, the Nine Tailed Fox was more of a hinderance than a blessing. He'd fall expanentionally as far as power goes if the Kyuubi is taken, no doubt, but he'd be able to use the full extent of his own power as well. Imagine how well he's come with focusing his own chakra despite the Kyuubi's restraints. Once it's gone, he can move much more freely and use his own skills and stamina to its maximum potential.
Think of how beast (pun intended) Naruto would be if he could do this. He learned Sage Mode even when the Fox conveined (because the Fox's chakra and Sage chakra can't go together), and it could last for five to ten minutes or so. If he used all of his own chakra, he could take in alot more sage chakra and have it last much longer, as well as activating it more quickly. When the shinobi tried to stop Naruto from going to the battlefeild, he stood still and activated Sage Mode in under five seconds--imagine how much more quickly he could do it if this happened. It's been shown to all he's truly mastered that technique and surpassed even Jyraiya in this matter. Jyraiya's Sage Mode was incomplete, and it took him most of his youth to learn it--Naruto completed it in a matter of weeks even with the Kyuubi inside of him, cutting alot of his own chakra off. He may be able to use more Rasen-Shurikens, more Shadow Clones, and even fuse with Ma and Pa with the Kyuubi not corrupting his flow of chakra (as well as theirs) should this happen.
Naruto needs to use more of his own chakra to focus on a jutsu as well as create it--one of the reasons why he needs shadow cloans. It would make sense if he didn't need to use as much chakra and stamina to use his own jutsus, as well as having acces to much more of his own chakra. Imagine the possability of creating the Rasengan by himself, and only one shadow cloan to make that jumbo-sized rasengan the size of a car or the Rasen-Shuriken. Sage Mode advances all jutsus, but using his own stamina to its full extent even in his regular form would be a nice upgrade, too. Kakashi, Jyraiya, and Tsunade all said that Naruto could channel his own chakra in a much higher level with the Kyuubi gone, and that it was holding him back until he could master the fox's chakra for himself.
Loosing the Kyuubi would suck for Naruto, but I think he could still do well without it.
