I don't know what else there is to add story-wise.
considered how slave route is ended, i don't mind doing adapted/edited book4 love route as book5 slave
but if talking seriously - i still wish epilogue would be just a bit longer, maybe short chat with dudes whose bodies we inhabited, to hear how they handled all this mess we leaved them and wtf they were doing while they were in our body during possession, and maybe final "few weeks/months/years later" slideshow, to see consequence for all choices and fate of rest of characters, kinda fallout 1/2 style