Good theory and that's something I can get behind. If Hiroto can steal abilities, he doesn't have to worry about finding enough loyalists to help him take control of any bodies that he needs to survive. He doesn't have to soul rip his stepsister; just steal her OP abilities and win. If Hiroto can transfer the stolen abilities to a suitable host, he can use the host defend himself instead of only relying on Narisawa to protect him against any threats.
The manga is "Ghost Hacking", so I don't expect it to be that much of a convenient ability, plus, the girl is placing abilities onto what's essentially inanimate objects, so how can she control them?
Maybe she drops a piece of her blood or something to make a connection between the object and herself?
Point being, just like we have "soul being removed" then "body + roa", maybe he is able to instead get "body" and "soul + roa".
In a Kingdom Hearts analogy.
There are:
- Nobodies (body)
- Pure Heartless (similar to a "soul" but no heart)
- Artificial Heartless (similar to a "soul" but there is a heart that is released when defeated by a Keyblade).
Right now we have pretty much no characters with no abilities besides these 2 girls that were just introduced, plus the ghosts that have no abilities but are friendly (one of the ghosts had an ability, and taught Hiroto about the hacking, but magician guy at least was confirmed to not have had one).
I doesn't make sense that ghosts would be able to use abilities, I mean, metal head girl, would she become physical?
So removing the Roa is kinda of a useless ability for him if he needs to take someone's body anyway. The fact that the original user can regain their bodies is certainly tricky, but the condition to lose the body, although largely unknown, is not something that he would be able to control, so even if he were to take over a body, and return the body to the owner but without the Roa, he would still need to take someone else to be able to use it.
So as a power up, I don't see the usability of whatever is coming, but another thing that came to mind is...
Nobody has more than 1 ability, yet the step-sister has 3, and we just got someone showing multiple abilities. What if this "technology" was already known by her mother? Mother is dead and step-father is... dead?
What if her 3 abilities are her own, her mother's and a third one? Or what if they were searching for the right abilities to take over and make step-sister girl into a super soldier of sorts?
So I think this event may be more about the mechanics of the world rather than a power up event right now.