It literally does mean that LOL.
Mia is a textbook Macguffin like come on now
She served her purpose. Depending on how the MC deals with Jake her purpose becomes even more of "I don't need to exist for the story anymore"
Jake dies: Mia is angry with MC and most likely plotting something...doesn't matter what she's just a humie who's gonna get slaughtered.
Jake is alive: She's angry at Jake and we don't see her again...why? Because she serves no purpose. If she gains powers thats cool and all but she still has no use for the story being behind so far.
She doesn't have SIN nor HERO's backing...she's just human. She won't get no revenge on MC if he killed Jake and even if she gained powers she's effectively...useless. Yeah pretty much.