Yeah it's the ultimate conclusion no doubt about it, it's very 90s isekai in that regard. The sibling rivalry I can see developing if the story is going in the direction of building their relationships very slowly and realizing that perhaps it's a third party that killed their brother, but even if they all realize that they're suffering together and share a goal the minute Moryeon is found out to be an omega his life will be turned upside down. we haven't seen the clear gender dynamics of this world but him deceiving the whole family alone is a big No, let alone sleeping with an alpha to hide it. After the reveal there's no way he can stay and live as an omega in this world
This is just my theorizing, but I assume blondie (the omega ml) doesn’t really like living in his time period. He doesn’t have any family or person who lives in that time to stick to. I feel like at the end they might go back to mc’s (black hair) world.
This is just my guess since I don’t see the sibling rivalry being resolved anytime soon. I also tho k this story follows the plot of, one person is teaching the other how to let loose and become more human. So I think going to modern times would free blondie from all the family troubles, and let him be carefree.
What do yall think?