I can see 75810 Upside Down reaching £500 within 18 months. Anyone disagree? It's liquid on ebay and stock is becoming thinner, without a full Xmas under its belt yet.
Quite a few Lego sets have been extended to 2023, that were originally scheduled to go this year.
75979 Hedwig is another extension, as is 75317 Mandalorian and the Child. I'm sure the usual websites will be publising a new article soon.
2022 Retirements for Ideas (as of now):
21318 Treehouse
21319 Central Perk
21321 International Space Station
21324 Sesame Street
21326 Winnie the Pooh
Saturn V is also schduled to go in 2022. Hope this helps.