you never know, jiraiya could come up with a way. or it could also be in a forbiddon scroll
Now also lets note that in no way are the Akatsuki members as strong as a hokage. Oro did kill the sands hokage and the leafs but he had no chance of taking the village without the aid of the sand. In that he also required Gara as a MAJOR part of the plan who was used in much the way they would want to use Naruto. If they could simply tear out the sand demon and put it into a already powerful ninja one would imagine they would have already done so.
if they arnt as strong, how come Orochimaru killed to kages, including the hokage. killing one person to killing a whole village full is different. would you want orochimaru to start a war on his own. he used the sand because he could minipulate them easy and use them to his advantage, why take overly bad risks when you can put the risk to your own life down. and that is what orochimaru is all about, the preservation of his life.