Can Nadal overtake Sampras and Federer in terms of Grand Slam titles?

Rafael Nadal has won 6 Grand Slams and is only 22 years old. Federer won his first when he was 22. Rafa to appears to be winning at an alarming rate. He might win all 4 Grand Slams (French, US, Wimbledon, and Aussie Opens) in his career when all is said and done. What say you?