While I don't think this bears direct continuation, I DO think you have created a Post_Voldemort world here in which other stories could be set, with some overlap with the Dudley-Daisy family.
I don't have a problem with Dudley naming their son Harry, assuming Daisy agrees, as Harry has already promised to make sure the child never wants for any necessity, and I could see some stories about the new Dursley child/children relating to their cousins, the Potters and Weasley.
I agree with some other reviewers that their is story material in the backstory of Hermione's relationship with the Potters, and other aspects of the Queen's honors to Sir Harry (can you say Victoria Cross? But that's been done. Possibly the George Cross, since Harry wasn't military, although the VC CAN be awarded to civilians, it is rarely done.)