well it might just be that im curently uncreative but such a great topic as this deserves atleast one reply so ill start it off i think luffy has to perfect gears 2 and 3 before hell bust out 4
"hummm perfected gear 3 = giant luffy "
but heres my guess i see it as something like a mix between two and three like a super strong super fast luffy but thats just my guess and as i said im not very creative right now
that can happen if he completely master gear 3 so not likely to be gear 4...i think it would be like he can transform into anything cause of his rubber body... no idea hahahahahah... nice topic but not many replies....oda is a tensai so cant match his idea...
as ive said before.gear 4 is gonna be super skinny and thin, but sharp.and luffy will learn the new move which he will call gomu2 shigan (copying from cp9) or
the tiny and quick luffy, where he can give a low blow to male enemy hehe
well gear 2 is speed, gear 3 massive power...hmm i think gear 4 will just have luffy not be strtchy but SUPER and im emphasize SUPER FAST and STRONG! idk i just that wud be sweet. Just have him whoop some butt. Maybe he will get a weapon like a pole with a monkey devil fruit power so he can whoop.