Toon force logically speaking should already be the top, it is reality warping basically which is something you see in high end beings in marvel/dc verses. It is broken without saving. Yet it is also horrible and that is why you don't see naruto, bleach etc. Have their MC get something so broken. This to say that if this is Luffy last form and he uses it in his final fight that final fight will suck. Instead of having the mc give his all ti beat the villain it will be another clown fiesta just like vs Kaido (I hope Oda has at least the decency to not resuscitate Luffy multiple times in his eos fight). So I hope will cone back to something acceptable like G4, 3, or 2. But he has to somewhat justify a non broken fight style is an evolution of a broken skill, which makes no sense but we will eventually see how Oda cooks this.