I don't know...I've always had a soft spot for Petunia I don't think she'll come out of her shell completely but maybe make some unexpectedly courageous gesture. It seems like the kind of thing JK Rowling would do, though, and she dropped a few hints in an interviews as well that there was more to Aunt P. than met the eye ... though I can't remember the quote. Also, there's that bit in OotP where Harry realises for the first time that Petunia is his mother's sister, and the only person in his family who understands who Voldemort really is..which underlines the fact that taking Harry in at all, knowing the risk to herself (and her Duddykins) , was really a very brave and un-Muggle thing to do. All things considered.