Most people don't hate Serra, they just realize (correctly) that he is not a legitimate champion and resent it. Serra's record is laughable compared to the top ww's. He hasn't fought very many top notch fighters and when he has he lost to them and not only that he managed to lose to a couple of cans along the way as well.
Karo must be physically ill every time he sees Serra with the belt considering how superior his record is, how he beat Serra and how he was supposed to get a title shot and then because Serra manages to win a couple fights against complete nobodies on a reality show he gets a title shot and flukes a win against GSP.
The question is not whether or not Serra will remain champ, he won't, the more relevant question is "How long will it be before he wins another fight in the UFC?" It could easily be years given the quality of fighters he is going to have to face now.
He fights Hughes and loses obviously. He gets to fight another contender after that, GSP, Diego, Karo again, Koschek, could be any number of fighters but whoever it is he is going to lose (because again, he is not a top ww, he isn't even top 10). He fights another contender after that, loses. That could be a year right there.
Having said that I like Serra in terms of his personality. He is forthright, he seems to have a sense of humor and he is a very capable coach. I greatly resent his being given a title opportunity when there were at least 10 fighters in the ww division who deserved it more than him.