By Safin's achievements I assume you mean US Open title AND reaching year end number one (since Safin was only number two) regardless of age? None of those on the list is even close. They must win the US Open, Hewitt must lose early, and they have to have a spectacular indoor season to do this, all the same time with Hewitt faltering. I don't see it happening this year. And who knows who will be hot next year.
If you mean by winning two Slams before Safin does...Haas has a good shot at both US Open '02 and Aus Open '03, but it's doubtful he will keep his head (and shoulder) screwed on long enough to do so. (Wishful think though) Federer's form is lacking at the moment and none of the others on the list seem to have the game to be able to handle both hard court and Rebound Ace with equal aplomb.