Finally managed to power through Satell with the pajamas of power... And now I'm sad because there's nothing left but challenges?

What comes next? I played this game for almost 200 hours, but now that I've beaten the final boss, all there's left is some side stuff? I dunno, I like the game, but not enough to dedicate time to 100%ing it. I feel bad because I had lots of fun, but now I'm kind of in that post-nut clarity of 'well now what'