Holy crap an ask! Yay! Thank you so much for your question!
Ok, so given he already has a quirk, Bakugo can't sustain ofa forever, especially if he keeps using its power. Though he trained for it like canon izuku did, his power has made ofa overfill. Its slightly dormant for now because he's doing all he can to contain it but everytime he even uses Explosion its basically shredding his inside like a grater.
We will see more of the ofa issue and izukus involvement in this arc, but Izuku will eventually interact with it.
Yes, afos ultimate goal is to wear down izukus will and mental state in order to move ofa (yoichi) in to take over.
So as easy as I can lay this out:
Afo takes over shigarakis body like in canon to steal ofa.
He separates yoichi from the other vestiges.
He puts yoichi into izuku.
He forces yoichis vestiges to take over izukus beaten down and broken consciousness.
Afo has his brother to torment again without that pesky kudo.
In canon I dont think this would ever be possible but now bakugos had ofa and izuku would be the 10th wielder, ofas going to be on steroids. The vestiges would be stronger, so who knows, its possible - or maybe afo is just cray cray and an extremely unreliable narrator lol.