I feel like Kid falls in the same category as Sabo, in that while he isn't a D, he shares a similar fate to the Ds due to his association with them.
At first glance, you can almost see a parallel between the rival trio and the ASL trio. In both trios, you have two members who are Ds and one who isn't.
Ace and Luffy are Ds, Sabo isn't.
Law and Luffy are Ds, Kid isn't.
What's more, while it isn't as apparent as with Sabo, who is a revolutionary, Kid's character is largely defined by his antagonism to the CDs.
His first big moment in the series was being Luffy's accomplice in the sabaody incident.
And post skip, what's the character who has been Kid's greatest adversary?
St. Figarland Shanks
Now who is this reminiscent of?
Both Sabo and Kid were sunk by Celestial Dragons. Just as both have a connection to the D clan and Luffy in particular.
Anyways I think that the big implication of this characterization of Kid is that, unlike what a lot of people seem to believe, Kid will be relevant in the final war. And this isn't just something I'm saying out of some sort of fanboyism, its practically stated in the manga.
The primary figures of the final war will be the same people who will take down Kaido.
The fact that he fought on the roof means that he will definitely be a primary figure in the final war. At least if we are to believe Oden.
Moving on, given that it is very likely Kid will be a primary figure in the final war, it begs the question as to what his motives will be for fighting said war. I believe that this will go back to his backstory.
Kid became a pirate due to the death of his childhood friend, Victoria Doruyanaika. My theory is that Oda will probably reveal that Victoria was actually a D; her name being Victoria D. Oruyanaika. Hence when Luffy tells Kid the meaning of the Will of D, Kid will decide to fight the WG in order to fulfill Victoria's will.
But alternatively, Oda could just be lazy about it and have him just get wrapped up in the war.
Nonetheless, I think there is a very real parallel between Kid and Sabo, which speaks to the fact that Kid will most likely do something significant in the final war. Be it defeat a Holy Knight or a Seraphim, or possibly even a Gorosei.
