Roger should have finished 2003 as #1, then he`d be @ 5-years straight YE #1 already.
I find this hard to back up, since Roddick had a stellar year in 2003 (outside of the clay season
). Andy performed better overall than Roger in the slams; Andy also won 2 TMS titles, while Federer won zero. Federer's performance at the final Masters Cup was out of this world, and there's no question he was the best in the world that week -- but Roddick outperformed him earlier in the year.
As for the question at hand, I certainly believe Federer could pull off 2 or 3 more years ending as No. 1. But will he be able to continue this streak of consecutive weeks at No. 1? (one of his most astonishing accomplishments, imo)