Hello Blizzard!
Shortly saying I am a former Ultima Online player from like 1999-2006 and also 2012-2020, but also a WoW player since the day 1 in 2004 (sadly I lost my old account back in days, current one has 6th Anniversary). WoW I have played all the expansions and maxed my mains every time.
My ideas are for upcoming Player Housing. I know that Blizzard already had a team working on this area. But did they have these ideas below. I was also the one, who did the 2 pages Word document about Player Housing couple years ago to WoW Council.
The ideas are simply the following ones.
1) Themes related to, or to players different and favourite zones
Players could choose the zones, where to have the home built in. Let’s say Undead Abomination wants to build home in Lordaeron or The Scarlet Monastery. Or Orc wants a slum from Orgrimmar, or Alliance wants some simple home from Stormwind either building a tiny, or progress into more wealthy larger home.
Players could choose from different plot size. Lets start from 9x9 and build it into 30x30 mansion. This could depend on how much in-game gold you have. Similar to the mount costs.
2) Architecture and Custom homes
We could design and CRAFT (via professions) our own homes by ourselves block by block like in Minecraft or The Sims, but within a Garrison type of a zone. Where other players could visit and gather around as a guild for RP purposes for example. This creates another unique aspect to the game.
As a guild we could even gather to search for block items together as puzzles and typical raids, or dungeons. To get something unique for single players, or guilds.
Via different plot size, design themes, or decor items homes could get into similar system as Transmogs are right now. You could even match your Transmogs with the house, or guild designs!
3) Add Lumberjacking and Carpentry as professions
Similar to Mining… I’m not sure, why Lumberjacking has not been a skill in WoW in these 20 years. Even Ultima Online had it since 1997 with different types of wood and custom wood types. Some of the professions even had Legendary level, which was 120 skill point. It needed real pure dedication to have that lets say 120 Legendary Tamer.
WoW had Lumberjacking experience first time in Garrison WoD I think with the starting quests, but never had it as similar profession as Mining, or other gathering professions.
Lumberjacks could make furniture and making Carpentry another new profession to the game.
4) Decorations and the new Transmog system
This one you already showed to us in the trailer. However I am afraid it is going to be just a few of items per class making players bored.
Similar to the Transmog system, we could have multiple different decors available in the world for us to hunt for them only for home interior design purpose as well, not just classes etc. Lets say blocks could be unique for our own home designs.
With this we could have unique blocks available for grinders as well.
Similar to what Hogwarts Legacy had.
With Lumberjacking and Carpentry we could also make more decors something similar as Engineering.
5) PvP and IDOCs
This could be something that would restore the good old World PvP in WoW and make it even better. This would be only for PvP servers.
Have a decay system in only PvP servers for personal, or guild homes. Let’s say the IDOC max time will be 6 months, where the home base starts collapsing within a random time in a week. Best IDOCers could calculate and mark runes to the best IDOCs and place best PvP players there.
If you get such IDOC as a guild, it would grant a great reward like a lot of gold, transmogs, mounts… Achievements what not.
However the problem at this would be the lag issues as with +100 players it will turn the server into a lag festival. I’ve been there thanks to Asmongold 
But if servers could be somehow fixed for this, this could be never-ending hectic world PvP action that world PvP enjoyers have wished for.
Another issue regarding this would be PvP players getting utterly rich in-game from benefitting players, who are quitting the game. But shouldn’t PvP deserve this already in WoW?
PvP needs something big. This Player Housing on PvP realms would make it that way!