I have heard Diagon Alley will be re-released this year. If this is the line, it would be a shame. Could be saved if the Tri-Wizard task is the Maze (only one they haven't made) and the Tower was good. These seem to be focused on the third and fourth books after the first wave was first and second, so they seem to be making their way through the books.
Although it's unlikely, I would love a Hogsmeade set. Similar to 10217 with 2-3 medium sized buildings. And (this is even more of a stretch) if this wave does well, perhaps a Ministry of Magic from the fifth book in the next wave. There is so much good source material in HP, and, although sets like the Hut, Knight Bus, and Express are slam dunks in terms of sales, it would be great to see some new stuff.