Although I'm also preparing myself for that kind of ending, it seems unlikely. Hikaru himself said that even though he was born there, he always felt like he didn't belong and isn't interested in going back. In contrast, we could interpret that he intends to stay with Yoshiki, with whom it already seems clear that there's a subtle but undeniable queer coded relationship between them.
So... Unless something goes terribly wrong, I wouldn't expect to see these two separated in the end :)
I think it will be something like the place won't allow Hikaru leave. now that Hikaru himself has acknowledged that he wants to get outta there and live in the mortal world with Yoshiki, it would hit the readers that much harder to see him unable to leave not because he chose to but because he can't leave I hope I'm wrong

Y'all, let's brace ourselves. I feel like Hikaru is planning on staying inside or smth like 'we all gittaget back to where we came from' n shi like trying that. He might be like 'u should go back to he mortal world as a human and I should stay in this shit hole cuz I'm not a human'. We're prolly gon get hit with a tragedy like that.