Strong "Vegapank next crew member" vibes, or one of his cyborg versions. I've a very long running theory since the pre-timskip when he was first mentioned that he might be the last crew member based on factor of "the bests in the world" being the heros and joining the crew. For example: Zoro the future (he actually already is since Mihawk is a fraud) world strongest swordsman, Nami is the best navigator in the world, Usopp is the best future marksmen in the world, Sanji is the best cook in the world etc. I'm not gonna list all of them since you get the point. And the point is, is that every single crew member in strowhat's crew is the best in the world in something without exceptions, every single one of them. And by that logic, THE BEST SCIENTIST IN THE WORLD should join the crew. At first I was reluctant to reveal my theory since lately so many "next crew members" theories failed, but this new revelation in this chapter with spoused Vegapank assassination forced me to reveal my theory. Now I'm not sure whether another old man is the best solution, but one of Vegapank's cyborgs/daughters might join especially of Vegapank ends up being killed by the WG.