You could say that Dragonball Z's SSJ3 transformation is to Luffy's gear 4th transformation, as we both knew or it was slightly hinted that they would have developed another form past their first/second powerups. I feel like anything past the ssj3 transformation(which was really well done btw) really pushed it, and the same can be said for if Luffy goes past a g4. I am fine if Luffy awakens his DF, as that is natural for every DF user, but if he needs to keep unlocking new gears altogether because opponents keep getting stronger then that is just an easy way for Oda to make Luffy stronger which I'm not a fan of.
I would rather him develop more on his haki though. When Luffy faced against Cracker, he said that his armament haki was one of the strongest he has ever faced and he was using G2/G3 punches. That's not acceptable if you hope to fight against a yonko 1 on 1. If Luffy is always going to be reliant on his gears then he needs to practice more with his other gears so that they don't look so weak compared to g4, and it's starting to get really annoying how the fanbase has only hoped for Luffy to beat all his opponents by only going g4. That should say something about his powerlevel.