There's some new information available pertaining to upcoming LEGO Harry Potter Sets for the 2021 Summer Release window. In total, there will be 10 new sets coming in mid to late-2021.
A few key notes on this data, the upcoming second wave set details are mostly complete, but we don't anticipate the remaining 5 sets (coming in late 2021) to be announced until the Summer/Fall, so for now we only have cost and set number details. As for set 76389 "Hogwarts Castle" it was originally anticipated as an update to the Great Hall (75954) set, which was expected to retire in 2020. However, due to the overwhelming popularity of the set, LEGO has continued its production run for a little while longer.
The Great Wall re-release will differ from the 2018 Great Hall in that it will contain a substructure where the Chamber of Secrets will be found. It will also include Harry, Ginny, Dumbledore, Nearly-headless Nick, Colin Creevey, Gilderoy Lockhart in orange robes, Tom Riddle, a teacher and a student. The updated 76389 is still expected for a Summer release, but that may change if sales continue on the current Great Hall set.
76386 Girl's Lavatory 217 Parts $19.99 Summer 2021
76387 Hogwarts Extension 397 Parts $39.99 Summer 2021
76388 Hogsmeade 851 Parts $99.99 Summer 2021
76389 Hogwarts Castle N/A N/A Summer 2021
76390 Advent Calendar 274 Parts $29.99 Fall 2021
76391 N/A N/A $249.99 3rd Wave
76392 N/A N/A $59.99 3rd Wave
76393 N/A N/A $199.99 3rd Wave
76394 N/A N/A $39.99 3rd Wave
76395 N/A 264 Parts $29.99 3rd Wave
We're going to report more sets that are coming in 2021 as the information becomes available, so be sure to subscribe to get notifications when new information is revealed!