While this is a real possibility, it´s not like current Quel´Thalas is doing well in this regard either. Eversong is mostly fine, while some places are filled with hostile mobs even though it would make sense for belves to clear them out since (Sunsail Anchorage, Duskwither Spire, Falthrien Academy, West Silvermoon), overall I can imagine the land looks almost the same.
However, Ghostlands, despite Dar´khan´s death at the end of zone´s storyline, is the only Scourge area in Eastern Kingdoms where zero progress against the Scourge seems to have been made and I think it´s all simply because the zones were never updated. While WPL is almost fully cleansed, EPL has islands of healed land and fortified positions, Ghostlands just keeps being the same even in modern questlines.
I doubt people back when Cata revamp was announced imagined that we´d be fighting off Scourge invasion of Tranquillien in 2022 but here we are.
And Quel´Danas is filled with demons, its only friendly area is half-draenei and Sunwell Plateau is inaccessible outside of raids, and even then it´s locked to its TBC era decor.
There´s risk of Midnight locking the zones into their 44 ADP state, but I feel like (unless it´s absolutely terrible) it won´t be worse than being locked into their 26 ADP state.