At this point, if not Sanji, then who? That is how I am feeling. If Marco and Law can heal Zoro, I would be happy to see Zoro fight King. Marco take one and then Sanji gets either perespero or Queen. But, at this point, if Zoro gets any more badass... Well, okay, I would love it if he just kept getting better and better lol.
But seriously, since we have not seen Jimbe, it makes me think he is struggling or losing. Marco is getting exhausted. I can't believe X Drake is still struggling to finish off Appo. It would be awesome for Sanji to be the one that helps turn the tide on a lot of the remaining battles.
I can understand Oda's predicament because the fans want the resolution of the defeat, and this necessitates huge power ups for all of the allies. Even the Tobi Roppou are a huge step up for the rest of the crew. So seeing Robin and Chopper get a long needed climax fight is going to be rewarding.
At the bare minimum, everyone in the crew has to power up (my bias is the exception is Jinbei, but more on that later). Thankfully, this is just the norm of every arc and the climax fights. It is just that the stakes are bigger, so Oda has to come up with bigger and better fight plots and the mechanics of how the power ups happen. And this is where Sanji is clearly nothing but latent potential. Either options of the Raid Suit or genetic enhancements would immediately be accepted and be big enough to explain his victory.
We still have all of the original options that reinforcements from the RA, different government/marines (Sword, other CP, or rogue marines), or even the Grand Fleet. CP0 was always the most direct since a mutual enemy creates temporary alliances. The opportunity to take down two Yonkou at once may be too big to pass up. Similarly, if Dragon and Sabo come, that makes things much easier.
As for Jinbei, he has never been challenged. Even when up against a Yonkou or admiral, he has been often shown to be "winning". The worst situation was taking the damage from Akainu to save Luffy. By this context, Jinbei struggling or losing seems unlikely since he has already shown that he is stronger than this tier (roughly Yonkou exec).
To overlap with Sanji, having Jinbei perform similar "Mr. Prince feats" to turn the tide would make him feel like part of the crew much faster. Oda has understandably tried to force this by having everyone look up to him as the reliable one (which is not lying/incorrect on any level anyway). This all goes back to how big the jump to Yonkou level is for everyone. And literally everyone (Jinbei might be the only exception since he is implied to be as strong as he needs to in order to take down King, Queen, Jack, or multiple Tobi Roppou).