That makes sense. I suspected that Lynette was teasing something like that after the credits.
I noticed below that you said you got carried away with the final dungeon, but I don't think it was too long at all. It took me a few sittings to get through the castle and the area below, but that's because there were so many side paths and hidden treasures and minibosses. That makes it a good dungeon. Most of the dungeons in the game aren't all that big, so the last one being an entire chapter in itself was a great change of pace.
One last little thing: I noticed a couple of shoutouts to non-binary people in Hotenshin. Thank you for that <3