Ordo
Enforcer of the Republic
Well you need to keep your theories straight.
You are perfectly welcome to dismiss Lucas as retroactively forcing his own delusional ideas on the saga. Alternatively, you can adopt Rex's position that "he [Lucas] is still on the level with the films as the 'holy grail' of Star Wars." You have stated this. Lucas has stated that this is ANAKIN's story....his fall and his redemption through his son. Not vice-versa. Thus, using your other logic that there is only one protagonist per film, Luke is never a protagonist. We are simply rooting for Vader to redeem himself while he's out blowing up planets and killing babies.
You can't seperate the PT and OT if you adhere to Lucaslogic (TM). Lucas has said they are one story.
Personally, I think Lucas is on crack, but this is your conundrum not mine. You need to decide what you are adhering to and what you are not.
I also think its impossible to argue that protagonists like Anakin and Luke are the ONLY ones. Kenobi is certainly a protagonist in the PT as are Han/Leia in the OT. Why? They are shown in extended sequences by themselves. They have their own plotlines. Yoda isn't a protagonist because he's never really shown apart from Anakin/Kenobi/Luke. Likewise Chewy is neither shown apart from Han/Leia. (not on a frame by frame basis, but for extended periods of time).
Leia has Lots of time on the death star to herself and Han Leia have the enitre middle of ESB, all of Endor, and the start of ROTJ to themselves. Chock that all together....was there no protagonist for 1/3 of the OT? Same with Kenobi...doesnt meet anakin until halfway thoguht TPM, has all of Kamino and some Geonosis to himself, as well as Utapau, some Coruscant too.
Now, these guys aren't the central characters in the story, not the MAIN protagonist (Anakin, then Luke) but they are protagonists nonetheless...definitely above supporting characters, espesially given the nature of these films as a saga.