This happened during the thriller era. It’s why he became addicted to painkillers.
Do you think he’d still be here today?
Well.. remove the painkillers from his lifestyle, and what directly killed him in OTL is gone.
But that's just one piece of the puzzle that made OTL's MJ what he was. The plastic surgery procedures - initially to repair the damage from the accident - spiralled.
Then there's the reclusive retreat into his Neverland property, which - underage companions aside (I'm *not* going into what allegedly happened, it's a whole subject in itself) - appears to be a retreat borne out of intense insecurity.
Without the accident, you have a Jackson that's not using painkillers, not going through an ever-increasingly bizarre series of plastic surgeries, and perhaps more confident off-stage.
I think he may have taken a break from the treadmill at some time in the 1980s to re-set & regroup after Thriller, and without the injury it could have been a time when he found some inner peace.