@BattleFranky69:
But Sanji's still fallen behind, so if he doesn't catch up now, he never will. And Zoro doesn't need his swords. He lifted a house and threw it at Daz Bones in Alabasta. He created the same whirlwind attack in the Davy Back Fight when forbidden from using weapons. The swords just enable him to cut, the power is all in him. So without any kind of edge, Sanji getting some kind of boost that would make him capable of having one of those elemental names like the rest of his siblings (Red Flame or something, like Reiju's Poison Pink) and having it become his signature would both put his strength and versatility back on the top tier where it belongs. Him having a flaming Rankyaku variation would be essential since it would give him a much-needed long-range attack, which Zoro has so many of already.
You are applying their feats of strength like its real life. I often see, "I can't believe Sanji's kept up this long without a weapon or devil fruit!" Those kinds of statements are absolutely embarrassing. Not saying you said those words but thats what its getting to. This is a story where the fist is greater than the bullet. Fist > Bullet.
Yeah Zoro lifted a house and threw it. Sanji kicked pieces of a brick tower of comparable size across a greater distance launching them at Oars. Who cares? I remember the cringe worthy statements when we first saw Zoro lost an eye. "Oh no his depth perception will be off, he'll actually be weaker!" Like seriously stop. Or who could forget "how could Luffy lose to Caesar twice? The training was for nothing!"
Sanji goes for glory(not just fighting, women too) and sometimes gets egg on his face. His place and role in the story is different from Zoro's where Oda doesn't put them in the same situations.
Then of course there is the Sanji VS Vergo fight. Sanji tried to tank a hit and got his bone fractured. If we think about it like its BS real life, shouldn't the bone grow back stronger? Mr 2 broke some of Sanji's bones and commented on it as if it was nothing new. In the fight Sanji landed several hits that caused Vergo to bleed and send him through walls. Vergo landed no such hits on Sanji. The gas comes in and they make a break for it. I thought that whole scene was handled by Oda very well. Vice Admiral Vergo was the biggest monster in the arc, tasked to keep Caesar safe. Being inconclusive for Sanji is lame in the moment but knowing the history between Law and Vergo that fight was only going to go to Law. Law needed to settle his Vendetta with Vergo. And despite Vergo not pushing Sanji to his limits or the brink of death Oda keeps Vergo a legit threat by having Sanji comment on how that fight could have gone bad.
I never really thought about it in the way that you put it but I love the idea of Sanji getting a flaming Tempest Kick. However with everything that we know of Sanji's abilities why does he need genetic enhancements? There has never been an issue of him running out of fire or not being able to reach a target since he's been able to fly. Also aren't most of the abilities from the children a result of technological gadgets that they actually wear? Someone may have to correct me there but I could have sworn that almost everything beyond Reiju's poison is from tech.
I guess this all circles back to Sanji's bounty but Oda is gonna Oda when it comes to that. Ever since East Blue there were some hints that Sanji has wanted a bounty, it was made very clear during Enies Lobby and when he finally did get one it was the work of the monkey's paw. Of course that was all about the picture used. The amount will probably always be a subtle point of hostility between Sanji and Zoro with Zoro always coming out on top. Then again maybe something spectacular would happen this very arc which gets Sanji even more notoriety and he gets a bounty equal to or greater than Zoro's for a short time causing even more animosity. Sanji doesn't need instant power ups in the form of latent genetics or the flame flame fruit to get his bounty up.