Joining this convo a little late, but I'm also American (though I'm from the Northeast). I do think young people are very familiar with Michael. I teach college and they are 100% aware of him and visually recognize him easily and have an interest in his music. But I agree that it's pretty surface level, still. I've had several students say they are big fans of him though and actually demonstrate knowing some deeper cuts (of course these are some limited anecdotal examples). Because of this, though, I see there being a lot of room for the biopic to catapult his discography. There is an interest already, so with more content put out there, I think it has the potential to really take off.
On another note, I've spent more time doing school work at coffee shops recently, so have been hearing more radio lately. I've noticed more Jackson 5 on radio stations, but have not noticed much Michael. However, after a few weeks off social media yesterday I popped onto the MJ subreddit just to see what was up and I saw a thread about hearing MJ on the radio more often in the US and several people who work retail were saying that in the last couple of weeks they are hearing *significantly* more MJ in the rotation including songs like Butterflies and Wanna Be Startin' Something, and Another Part of Me (i.e. not just Billie Jean, Beat it, and MITM) so that's kinda cool.