As much as I would love to see the bisexual harem (Chadruma could definitely pull it off) I really doubt the mangaka's gonna have the balls to do it. So many hint at the harem, they have a whole fuckton of people all gunning for the protagonist, but outside of (usually trashy) isekais it doesn't usually come to any sort of fruition.
I can see Sullivan having some stupid line about 'give me as many cute great grandchildren as you can!' though.
I very much expect Amelie to be his one true waifu. And who could blame him!?