Let me start by saying the Vinsmoke Family story line IS FAR from over. Oda purposely didn’t make it as the side family Sanji has to meet once and settle it and move on but instead gave them a history that’s yet to be revealed.
So why do I believe the Germa/Vinsmokes need to make a comeback?
1- Simply their history is rather important for the overall picture and the link to the World Government. This is a nation that ruled over an entire Sea 300 years ago under the name the “Germa Empire” and got defeated by someone (probably World Government but it’s still vague) and they are not able to set a foot on their homeland since then and there’s multiple references to 66 days maybe it was the length of the battle that they lost or something. Overall their history seems to be extremely important either in the World Government plot or Revolutionary Army plot later on.
2- Sanji’s acceptance of his family. This has to happen just like when Sanji said to Momonosuke “you declaring YOUR NAME was amazing” few chapters ago. Sanji has to do the same to fully move on from his family and he has to declare himself as “Vinsmoke Sanji” and while you could say he can do it without the Germa and Judge being present it feels like it would be more powerful if they were there. Also Sanji uses the Raid Suit and he needs to accept that as well.
3- Judge has links to scientists all over One Piece and Queen seems to be one of them AND I still believe Judge has a lot more to give as a character mainly cause his story mainly revolve since he was born. He was raised to take vengeance for his people and since young age he became a brilliant scientist that was willing to do anything to Make Germa Great Again (MGGA) and he went as far as to make scientific changes to his sons.
And finally how would the Vinsmokes be in Wano? Well it’s as simple as we left them to fight the Big Mom Pirates which was a lost fight and they 100% got captured and put in Mont’dor’s book prison and Mont’dor is one of Big Mom sons that has been shown to be here in Wano.
*Theory by Rocks D. Buggy