Brief disclaimer: I haven't beaten the game yet, so I apologize in advance if I suggest something the story already addresses.
And the cliche with that, in particular, is that the first BBEG being defeating was either planned or needed for the next BBEG to come into power. For example, maybe there's a counterpart to Nori (that neither her or the director were aware of) that was also suppressed as a side effect, and lifting Nori's suppression means the other entity is now also unbound. Alternatively, there were predecessor test subjects or whatever with an unusual power that were either under the director's control or hid their existence until he was defeated. Thirdly, something that shouldn't be possible happens, because literally magic is involved and the events of the game had no precedence.
read at your own risk, this whole comment will be plagued with spoilers.
the director is supposed to be nori's counter part, and the director gets 'absorbed/disassembled' by the MC at the end. so unless the energy
from absorbing the director wasn't properly split amongst the girls and nori as intended to save MC's life. which imo would make nori more incompetent about her powers than i'm comfortable with. then i'd say your guess could hold water. because energy always has to go somewhere. and it could be a setup for mist2 with one of MC's kids/grandkids being the new protag. presuming it would take longer than a decade for the energy to consolidate and form something anew. however i must point out that any
third split off nori hiding themselves watching the chips fall. probably wouldn't be as hostile towards MC, harem, and kids. mainly because
there was a prime opportunity to kill them all and steal all of nori's power right after the director gets absorbed. so yea, doesn't add up imo.
alternatively though, you made me think of another idea.
the director and other fused egos get reborn as MC's kids... considering the time table at the end, and when the
pregnancy for mia, lily, and nori are presumed to have happened... yea... might lead to some early game of thrones like plot.
*looks in jamie's direction*
as for your other idea, we saw all the proceeding test subjects though...
one of them being a meat tree, the other a human transformed into what might as well be a mindless chutulu minion. going by the research papers MC scavenged, the tentacle monster was the proceeding experiment before nori was 'born' in earth's dimension and split into two.
as for your third point... eh? most of the magical nonsense fallows the laws of energy transference. (forgot the proper terms) with the only exception being MC's protag powers and weaknesses. so i don't quite think your third point would be even possible...
