So a crackpot theory regarding gear 5, if that will be a thing:
Honestly, I don't see what else luffy could do with his body to further boost himself. So far its either pumping air into his muscles or bones or accelerating his blood flow. And.. that is it. There should be nothing else that determines a person's strength or speed that luffy could manipulate with his ability. I suppose there is haki to increase his hardness and manipulate his elasticity but presumably that is already a factor in his gears, specially gear 4.
So... the question for a future gear would be what luffy could manipulate and how to result in further strength, speed and endurance. A theory I've written before is something like giantman form... Basically luffy just combines all gears and becomes a giant. He has already used techniques which apparently combine gear 3 and 4 so this would be a step further.
And now a new theory... Following the principles of laid before by a hypothetical giantman form. Compression man. Basically rather than inflating everything and turning into a giant luffy pumps air into himself and rather than simply inflating, he uses his haki to remain in a basically human form. Thus increasing his bone and muscles density. Basically the compressed power of gear 3 and 4. And potentially gear 2 could be at play as well. In my head luffy would also be able to simply release his muscles compression on contact with an enemy this his limbs dramatically increasing in size upon contact for extra swagger when fighting. Basically, this would be the culmination of luffy's fighting style, condensing everything he has developed into a single absurdly powerful form. I suppose this form isn't mutually exclusive with my previous idea of giant man so perhaps luffy could switch at his convenient between the two. Since he'd simply have to manipulate his elasticity to switch...
Honestly, I don't see what else luffy could do with his body to further boost himself. So far its either pumping air into his muscles or bones or accelerating his blood flow. And.. that is it. There should be nothing else that determines a person's strength or speed that luffy could manipulate with his ability. I suppose there is haki to increase his hardness and manipulate his elasticity but presumably that is already a factor in his gears, specially gear 4.
So... the question for a future gear would be what luffy could manipulate and how to result in further strength, speed and endurance. A theory I've written before is something like giantman form... Basically luffy just combines all gears and becomes a giant. He has already used techniques which apparently combine gear 3 and 4 so this would be a step further.
And now a new theory... Following the principles of laid before by a hypothetical giantman form. Compression man. Basically rather than inflating everything and turning into a giant luffy pumps air into himself and rather than simply inflating, he uses his haki to remain in a basically human form. Thus increasing his bone and muscles density. Basically the compressed power of gear 3 and 4. And potentially gear 2 could be at play as well. In my head luffy would also be able to simply release his muscles compression on contact with an enemy this his limbs dramatically increasing in size upon contact for extra swagger when fighting. Basically, this would be the culmination of luffy's fighting style, condensing everything he has developed into a single absurdly powerful form. I suppose this form isn't mutually exclusive with my previous idea of giant man so perhaps luffy could switch at his convenient between the two. Since he'd simply have to manipulate his elasticity to switch...