Aurors will still be needed. they are the special agents of the wizarding world. they deal with dark wizards, and i must assume there is a subsection of the auror office that is mad eup of more general law enforcers. So the Aurors are like the FBI in the US, you know? they will still be needed, and will still be there, waiting for the next Voldemort to come along, and until he does, they will be taking care of larger wizard crimes, like murders and what not.
then again, i could be wrong and the Aurors are the police of the wizarding world. if this is the case, they will no longer have an all out man hunt for voldemort and return to general law enforcing.
no, hold on, scratch that second one. i just remembered an the trial chapter in book 5. harry asks about the jinxed toilets, and asks if it will be the aurors who catch the guys and arthur told him it wouldnt be.
which reminds me of this: the aurors were hunting Voldemort before Harry was born, and then the curse rebounded and tried and failed to kill voldemort, but everyone basically assumed he was dead. and guess what? the aurors were still there! OMG! if this comes as a surprise to anyone then your all forgetting shacklebolt (he's auror!) and Tonks (OMG SHE IS TOO!!!) and guess whic hbook we met them in? thats right, we met them in the book where the Ministry of Magic was trying to make it out the Dumbledore (God rest his soul) had gone senile and that harry was just trying to stir up trouble to get attention and that his was a troubled child. so yeah, if the Aurors only existed to catch Voldemort, i am pretty sure both Tonks ans Shacklebolt would have been unemployed when we met them, or more likely would have had other ministry jobs. hope that helps with a twist of No dream job for Harry if he survives to take up a proffession.