Hey Hopewrites, in her expansions on what happened to who beyond the books on places like Pottermore, JK does mention Dudley post Deathly Hallows. Harry as an adult will sometimes visit Dudley, they don't speak much, harry's kids hate going there, but it is clear that despite everything, Harry does care about Dudders. That's kind of the whole point to Harry's characters though imho and the reason every book returns to Privet Drive.
And as Dumbledore once said - given his awful upbringing, the awful people he continues to have to live with in holiday time, it really is extraordinary what a decent, loving boy and later man, he turned out to be. The Dursley's are there to show us what Harry could have been. Imagine if he had indeed grown up in the magic world, feted as a hero, treated almost as a Prince, he may well at 11 have been a very arrogant, privilaged and unpleasant young man, someone very much like Draco in fact.
I suspect that for the love protection to work it had to be wherever Petunia calls homes, there are distant relations of Harry in the Magic world, there could well be in the Muggle world, but Petunia was Lilly's Sister, and that was clearly the closest relation by blood harry had.
And the thing is, at the end of the day, Harry did get a version of a loving, caring home, to help with that anger. At the age of 11 he went to Hogwarts, made his first friends, found his first true Home, and came under the care of adults of genuinely cared, and certainly in Dumbledore and Hagrid's case loved him.
For me one of the most moving and "something in my eye" scenes in the entire set of films is in Philosophers Stone, Harry on his first night, everyone asleep, and he is sat in the window, stroking Hedwig, there is just something wonderful about the scene, Harry is Home at last.