I'm thinking Kidd may become a shichibukai, though its tough to say if he will listen to any orders (not as if any of the shichibukai do lol) ... but yeah I can totally see Luffy beating up Kidd - then Kidd becoming a shichibukai to somehow get at Luffy.

Also Buggy is likely since the WG contacted him - also without that dumb hat he does look pretty cool.