I suspect that we will rather quickly get a definitive answer from Boeing as to the provenance of this part. Given the number of minor changes that always take place during production, I wouldn't be at all surprised if they can, absent a serial number on the part, at least narrow this part down as coming from a range of line numbers.
Moreover, the condition of the part may yield some answers as to how the aircraft went down.
NBC News in the US is definitively reporting this as a part from a 777.