Personally, I'd much prefer Anakin be the older, previous pupil and the other, current one be "Hayden".
This is how my dream edit/reshoot would play out.
We get to see the young "Hayden" overshadowed and jealous of the older, more experienced and more talented favourite, Anakin Skywalker - the best starfighter in the galaxy, a cunning warrior and a really close friend to Obi Wan. Obi Wan is overly domineering and expects more from "Hayden". Constantly expecting him to meet the same standards as his previous apprentice.
In film 3 we see glimpses of Jedi being murdered by a hooded figure. They are being hunted.
We naturally think it's "Hayden" that turns to the dark side and becomes Vader - which isn't hard to believe as he's established as a whiny jealous little shit. Hayden acts suspiciously on screen and is absent for long periods. His excuse to Obi Wan is that he's investigating something important (or something similarly ambiguous).
Anakin announces to the council via Hologram that he's discovered that "Hayden" is behind the killings and that he's off to confront him and end it once and for all.
We see Anakin walk into a room with "Hayden" looking out a window. With the camera behind Anakin we see him ignite his saber and the door shuts in front of us.
We only see one hooded figure leave the building, which explodes and burns as the dark figure walks away. The council then believe Anakin to have been killed confronting "Hayden" who they know from Anakin's holomessage has turned to the dark side.
Of course, come TESB, it becomes clear that it wasn't "Hayden" that "betrayed and murdered" Anakin, but it was the other way around.
I've thought a lot about this, and believe it's the best way of solving every problem created by the current prequels - the current Anakin isn't painted as any of the things Obi Wan describes Luke's father as in ANH, so we need a new one and the current Anakin becomes the other apprentice.
Impossible? Almost certainly.
But I think not actually SEEING the turn to the dark side not only solves the current problem of us knowing explicitly that he's become Darth Vader, but also gives the reveal that much more impact in TESB. With Hayden as Anakin, it's no big surprise - we hate him. With a new nicer Anakin who seems a great guy up until his apparent death, it's so much more of a shame and gives more weight to the corrupting power of the dark side - he's conspired against his own friends while keeping up the facade of being good until the time came to frame and kill the only person to know the truth, and disappeared, adopting completely the mantle of "Darth Vader".