Here's something no one is talking about. X Drake for nakama is a dark horse. Most people don't even consider him, and for good reason, but I think it's possible for him to be a Robin situation.
First of all, his plotline is strange and seems unresolved. He was one of the supernovas who was given more importance, but despite being a flying six and being revealed as an under cover spy, he's been the least important supernova in Wano. He acomplished nothing and had no real goals. He got betrayed by the world government, and then just disapeared. They made a huge deal about him joining the alliance, and then nothing happened with it. I've never been a Drake fan, but this really doesn't seem right. There has to be more.
Also, Drake has no crew, and might not be able to return to the marines. After Wano, he will be left with no purpose. The only connection of his we knew about was Coby. Maybe he will try and go with Coby's idol? Why even have the Coby flashback otherwise when it made sense for him to fight with the alliance anyway?
I think it's possible he will ask to join the crew, perhaps with ulterior motives as a Marine at first, and have his character arc in a Marine related arc in the future. Probably an arc related to Vegapunk.
I don't necessarily think this will happen, but I think it's worth considering.