serialized manga format as before. no rough drafts left by Miura, but Kouji Mori (supervisor, Holyland mangaka, close friend of Miura) knows the entirety of the plot and they are working off of it. Miura's production studio producing it, will try to write "as not to deviate from Mr. Miura's own words."
That's usually how it is with these sorts of things. Hopefully the end result will be good.