I have a theory that (if we do get a chapter dedicated to the Light World) there will be a combat system like in the Dark Worlds! Otherwise, why else would Kris have stats outside of them? What's more, we've got a lot of Lightners that seem to have some significance that don't seem to be in the position to become Dark World companions. Maybe they could be Party Members in the Light World instead!
Of course, I'm not sure how attacks would work considering how magic seemingly doesn't exist in the Light World, but as shown in K. Round, Rouxl Kaard, and Giga Queen's boss fights, not all enemy combat has to be magically tied.
Besides, Toby has to keep us from getting bored SOMEHOW
"Then he can just, not make a Light World Chapt-"
NO! THAT'S THE BORING ANSWER!
What do you guys think? If you disagree, I completely understand! This is a pretty farfetch'd theory.