if you think it's temporary than i don't think you understand what is happening. first off, you cant destroy the juubi or bijuu therfore there will always be a need for somebody to keep that power in check. for now there will be no need for the likes of naruto or sasuke to go on missions because there will be true peace after this war. but as all people won't buy into this there will still be people who want to cause chaos and war, someone has to stop them. the sage has given them this power and the only way for them to lose it is if it's taken some way. also what kind of a time limit would be on these powers? what if it takes them 2 days to beat madara? if the sage intended for it to be temporary did he give them enough time to defeat madara? making it temp doesn't make sense. this is a shonen, characters are meant to be OP, it's not like they were ever really ninjas to begin with. when was the last time you saw in a movie or whatever, a ninja that shot fire out of it's mouth? they were never suppose to be like that. if anything this has proven that power like this needs to be in the hands of people who will only use it for good, although i question giving sasuke such power but whatever.