It's too soon for him to play another real legend.
Why? He's an actor, isn't he? I didn't see anyone complaining when Anthony Hopkins played Richard Nixon, Pablo Picasso, and John Quincy Adams in short order.
Hopkins didn't win a Best Actor AA for any of those roles nor was he constantly featured in the media for having the performance of the year. Foxx was front and center on every award show from the Grammys to the Oscars.
Anyhow, it appairs Foxx's plate is full with other film commitments over the next couple of years.
No, no one complained. But I wonder if the reason is because, not too many people saw him in all three films back to back at that time. And based on each respective film's box office receipts that could very well be. I know I didn't. Surviving Picasso was not even released anywhere near my city and I don't think it is even available currently on DVD.
Foxx would be good but I discounted him because he's pretty much booked through 2007. Unless Redford and company is willing to wait 2 years to start filming with a hot star, it might just work. If not, they'll have to find someone else.