Foden will go on to have a far better career. He may already have. He'll certainly have many more accomplishments.
Not sure I'd say Foden is or will be better, although he's certainly a top class footballer. And it's only an argument because for as good as Gazza was, he never hit the heights his talent deserved. Gazza should have been up there with the Zidane's, Platini's, Laudrup's and the likes. He had everything, a generational footballer.
A bit strange to say that Foden will be three times the player when, for me, Bellingham looks the closest thing I've seen for England since Gazza's hayday.