you could probably make an entire expansion out of scraped content
spider underground zone from wotlk that was scraped and turned into a dungeon
quel thalanar zone from vanilla still not completed
stormwind vault raid completed but empty
Zul'Drak troll raid
3 scraped islands from draenor
vash'jir raid
emerald dream map+zone half completed
lore characters such as multiple gaurdians and titans that we read rumours about but never show up ingame
fun exciting things they use to attract you to a new expansion is new dances and dance studio
all of that would equal to 1 whole expansion that would genuinely last 1-2 years