I wonder at times if the reason why Buggy has become a Warlord is to keep him safe. The seas are much more rough for all pirates now and the new age has begun. The weak most likely won't survive. It may also be for some other purpose in the future when Luffy starts a war.
I also believe that when that war starts, some or the majority of the warlords will ditch the marines/WG and side with Luffy. That includes Hawk-Eye and of course Luffy's future wife, Boa Hancock. What I'm a bit worried about in this case is the new warlord. Who could it be…?