With the recent Kirin Tor quest, pocket dimensions seem to have been emphasized (at least to me). So I would assume that they will be using pocket dimensions for additional game mechanics/lore such as;
-New location for Dalaran city.
-Player Housing
-“Escape pod” for when Azeroth under goes a massive geological/geographical change.
What else could they use them for?
This! This would work so well as an opportunity for building custom housing environments and such.
I’d use a pocket dimension to hide a time machine that the Bronze Dragonflight doesn’t know about.
…like a painting
The final home city for Gnomes.
Where Gallifrey is hidden 
Timelord race when Blizzard?
Our inventory literally are pocket dimensions
Clearly they’re already using them for my mounts, hunter pets and battle pets. What else would an “Interdimensional Pet Repository” be?
Especially when we had multiple horses in our pockets
Gallifrey Stands!
Those are the Bronze Dragons.