I heard him say in another interview (Charlie Rose) that he didn't intend to be an "old man director," as though there's something distasteful about being an old man director. Sounded a bit like ageism to me, so I didn't care much for the sentiment.
He said somewhere that he was multiple times disappointed with genius directors later work and he wanted his filmography to be top notch, so if a youngster in 40 years picks up a random Tarantino film he would be astonished.
I would actually like to see him stop directing, because he would write more. His analysis of There will be blood was very eye opening.