Color Scheme & Abilities:
I'm gonna go on a wild prediction here and guess that the new guy's gonna have a Green color scheme I'm basing this off the pothead Kizaru, and Fujitora's Purple Kush
Light, Gravity, & Time are all part of the theory of General Relativity made by Einstein.
It's much easier to label the Pre TS trio into color schemes, since Ice=Blue, Yellow=Light, Red=Magma, and these are more obvious, as they have the dynamic of the Elements, and in this case, the Logia.
It seems like the Post TS trio including Kizaru is gonna be based off of a relation of energy in physics.
It's harder to label invisible & intangible things like gravity or time into color schemes, but now we know Fuji has the purple scheme. Time is usually portrayed by a grayish and empty, dull hourglass formed image. But I also think green can be a unique color representation of time, since green represents the plants, roots, trees, and nature in general. All these things including nature are usually images used to represent growth and nourishment. The growth of a plant rising up is almost inexplicably linked as a very symbolic manifestation of the basic concept of growth itself. As plants become old, they wither and wrinkle.
I don't know, just playing with ideas here. I'm thinking if the new Admiral can control time, it will be really hax and overpowered, but I'm trying to think of a way where Time manipulation in One Piece wouldn't seem too typical, cliché, or overdone..knowing Oda, if he were to choose Time manipulation as a power(which he's done so in small extents like Foxy's fruit), then he would bring an original twist to it.
So what do you think his abilities and color scheme will be? Wanna throw in any predictions?
Personality: I hope and predict that this Admiral is going to be an Absolute Justice Marine like Akainu, but he should have his own take to the doctrine, which doesn't make him just some follower chasing Akainu's beliefs. He should retain his own individual sense of self and ideals, rather than being just a puppet. Look at Fujitora, he seems to be a balance minded individual, and he actually thinks for himself, and not just from the views of his superiors. I'm hoping that the final Admiral will be just as independent, but in a more aggressive and brutal way, following the Absolute Justice doctrine. Fujitora was shown to be similar to Aokiji to some extent, in that he cares about the safety of civilians, and has a sense of Moral Justice. Then we have Kizaru who's still repping himself and his own justice, so that leaves the last Admiral position, who I'm hoping is more like Akainu, except not just being some "For the Greater Good", or just another "For Justice" character. Make no mistake, I'm not saying that Akainu's character is one dimensional at all. I'm not, and I think he pulls off that trope very well, as it fits his explosive state of mind. But it really only works well for him. I'd want the final Admiral to follow the same radical justice, but on a more personal basis, and not just someone who caters to Akainu's sense of justice.
Plot Relevance: I'd want this guy to be at the forefront of the New World battlefield and front lines in the situation. It will be cool if we see an Admiral with a short time rivalry with one of the top Revolutionary Commanders, rather than just having this Admiral fight Yonko crew mates again. Or Oda can still have him clash with Yonko or their crew members, and develop some original and golden interaction between the Admiral and said Yonko crew member, like Kizaru/Marco, or Akainu/Ace.
And if he stays long enough to make it to the later stages of the series, I'd want him to be taken down by either Kidd or Law when they are at that level yet. It will be a satisfying way for Law or Kidd to get stronger and solidify one of them as a full fledged New World god, by the end of the series. Just don't let the M3 hog all the spotlight.