pretty sure that kishi will explain everything, probably the emotional development of the characters will take the lion's share and then what's left will be about maintaining consistency. that out of the way: plot holes are plot holes, retconing material can be used in the way you said but it is also considered bad writing. not saying that bad writing doesn't mean successful or popular or 'wrong in any way imaginable' but it is not a technique highly regarded amongst professionals and for a reason. actually more than one reasons. it shows lack of imagination, sloppy planning and writing of the preceding material, inability to maintain consistency, etc. as i said apart from what fans, like you and i, think plot holes and retcon are not highly regarded amongst the professionals, it is considered a poor writing technique. given how long kishi was playing with Tobi's identity it was bound to lead to problems. at least now that it is all out he can still give some great character development.