First and foremost, irregardless of the Gaban/Sanji parallel I think it ultimately depends on whether Oda views ACoC as a necessity to have at the top level for end game fights which Sanji will obviously be involved in. If the Gorosei and Imu for instance are the end game opponents for the M3 and all of the Gorosei have ACoC then Sanji will most definitely have it.
I rate ACoC as a significant powerup but it's just the peak of one branch of development in a series with a variety of abilities. For DFs for example, there is Devil Fruit awakenings (I mean can you imagine how filthy a Logia awakening would be especially with a destrutive logia like the Magu Magu no mi

).
Kaido might tell you that Haki is the way to reach the peak whereas Blackbeard would tell you that it's Devil Fruits. There's not just one set route to reach the top. I mean just take Luffy for instance even with ACoC dude has a broken god fruit on top of that lol. Luffy himself is evidence of the fact that it would be impossible to reach the top of the current era with just ACoC.
That established, I don't think Sanji necessarily needs ACoC to be a powerful top tier, just like the Admirals have broken fruits and might have awakening on top of that, Sanji could very well be on a separate development route to take him to the top. Could be his modified lineage factor and the power of love for instance.
What is certain though is that Sanji is going to reach the top irregardless of what tools he uses to get there.
Again I hate to sound like a broken record but first and foremost Sanji is relative to Luffy and Zoro and this is what is ultimately going to be determine how high his peak is irregardless of whether he has ACoC or not.
With regard to whether Sanji will actually get it, I don't know. As opposed to Gaban who is just a regular human, Sanji is a modified human that also wields the power of love so don't think he needs it per se. Will ultimately depend on whether Oda views it as a necessity for him to have. Right now though there is a very high probability that he will get it.