FWIW my guess is that Boeing are looking at 2 repair options for the fuselage.
The first would be to perform a complex bolted repair, I don't believe a bonded repair would be permissable. The repair plate would be (guessing) at least 12 ft by 3 ft, and possibly compound curvature. If EA accepted a non-flush repair then it could be fitted on the outside, a much easier option, but with some drag, and therefore performance, penalty. And it would be visible. If they demanded a flush repair (i.e. non visible), then the plate goes on the inside, and has to accomodate all the other fuselage structure, frames, stringers and whatever, as well as whatever systems are there, much more difficult. This supposes that the only structure damaged is the fuselage. It seems to me the fin (VS) may well also be affected . . .
The other option is to replace the damaged fuselage sections completely. This would appear to be the aft fuselage and tailcone sections, all 75 ft of it. The big advantage would be that all the fire and smoke damaged items would be replaced, with no concerns for repair integrity, future maintenance, inspections, etc. But it would be a massive job indeed, including the need to jig the fuselage, remove and replace the empennage, all the systems, interior fittings, etc. And to add to the problems would be sourcing these sections; I would have thought that all major components like these are already assigned to specific aircraft in build or planned, for some years ahead.
My guess is that the 2nd option is completely unviable financially, but who knows what Boeing are thinking. As someone has already said, the bad
PR from writing off an aircraft so early may be too bitter a pill to swallow.
Just my thoughts, with no deep knowledge of Boeing or their aircraft.