actually that would be kind of cool, I'd really love to see a meeting with the big's of the new world, with some long standing repercussions…. still I'm not sure how long something has to be to be an arc, a few chapters of the bigs of the world talking might be cool, but I can't imagine an arc
I'd need to know some facts first:
who would be the central characters be, what would be the motivation from a storyline standpoint be, what are they trying to get across, how long does it last etc etc
it's been said a million times before, anything can be done well, even crazy unorthodox ideas that sound stupid at first (like superior spiderman), as long as the writing team is capable, in this case the writing team is oda who I have faith in....
but it's kind of the exact opposite of what one piece is, a huge thing you notice if you reread one piece is how much the character's really run into the plot, and start to change the entire world (little by little), but without even trying to, it's a little crew (the straw hats) who go to island to island looking for fun and adventure and some how get sucked into the events that are transpiring on the island. the only reason they went out of there way to stop crocodile and risk their life doing so was because through a series of unpredictable events (to them) they became good friends with vivi, vivi good, crocodile mean to vivi, crocodile bad, must be stoped
bad guys cp9 frame us for murder.... okay we could go to next island... but they took our nakama
they don't mean to unbalance the system of the shichibukai by beating them, or to severly hurt the name of the world government by destroying eneis lobby, even the events that are unfolding now they either fell into them, or went along with laws plan, just cause Luffy likes the idea of an alliance
there's a reason the most time we get away from the straw hats are a few chapters after some big event they just took place in to show us the consequences to their actions, so although Oda could do it, I find it highly unlikely
EDIT: my writing might not be to great right now,I apoligize if that's the case, kind of tired