Let Me Play as an NPC?

[Rymm]

I'd imagine the idea is more akin to how vehicle controls are or how WoW does it.

I know you were just citing WoW as an example of a way it could be done, but it should be noted that vehicle fights in WoW were largely despised by the player base. It's why Blizz pretty much scrapped them in recent expansions, especially in multi-player content. In fact in the first 5-man dungeon they tried to implement vehicle combat in, including an entire boss fight, they had to go back later and add a previously raid-exclusive mount to said boss's loot table, just to bribe people into not bailing as soon as they zoned in.