Mr. Weasly will become the new Minister of Magic
Reasoning for this: Read the Quidditch World Cup sections in GOF and the aftermath of Harry's Trial in OotP. In spite of what his children think of his position within the ministry, Arthtur Weasly is well liked and respected. He has no desire for "power" but he will serve, especially if Dumbledore recommends him which is why I believe that Arthur Weasly will be the new Minister of Magic.
The Half Blood Prince refers to, not Harry or Neville but Seamus Finnegan. I'm using the movie to support this but it's also mentioned in the book. "Me Dad's a muggle, me Mam's a witch." Seamus iis truly a "half blood" wizard
Harry is a partner in the Weasly Twin's joke shop.
Although Harry just gave the Weasly twins his tri-wizard winnings with no strings attached(save Ron's new dress robes)I believe that they made Harry a full partner.
One of the Weaslys will die in book 6
It won't be Ron or Ginny or even Percy but one of the other four older brothers(sorry can't remember their names at the moment).
Ron will betray Harry either in book 6 or more than likely book 7.
I think this will more than likely be a result of Ron deep seated resentment of Harry, his wealth, his fame ect. And the one big moment in Ron's life winning the Quidditch cup, Harry had more important things to do.
I'm probably wrong on all of these, but hey that's what predictions are for 😆 😆