Wittgenstein mentions the "dream of Socrates" in § 46 of the Philosophical Investigations. But can it be said that in what follows - at least up to § 78 - he comments the questions Plato raises and discusses in the remainder of his Theaetetus?
It seems unlikely to me that Wittgenstein had intended to comment on Plato (or any other of the "great philosophers"). In my view it is more plausible to treat the references to Plato, Augustin etc. as placeholders for his own, earlier views -- a view that is argued, among others, by Kienzler (in his book "Wittgensteins Wende zu seiner Spätphilosophie"). The dream of Socrates has clear analogies to the metaphysics and the picture theory of the Tractatus, so it is particularly apt to function as a placeholder to comment or discuss his own, earlier views. (Moreover, there do not seem to be references to other parts of the Theaetetus, are there?)
The opposition between Plato as seeking the beginning and Wittgenstein the end of philosophy is very suggestive. I also appreciate very much the placeholder-idea. It seems to be congruent with the Introduction to the Investigations, where Wittgenstein sets out to contrast none but himself and what he calls the “grave mistakes” in what he wrote in the Tractatus. Also Wittgenstein’s own assessment of his work as mere “sketches”, his failure to “force” his thoughts “on in any single direction against their natural inclination” make it improbable that he would systematically have followed the structure of another author’s work. Yet there are the analogies between the dream of Socrates and the picture theory of the Tractatus, as Dr. Huemer says, so that an analogy between the Theathetus and the Investigations is not completely out of the question. On this basis I have reviewed my perceptions about a certain parallelism between parts of the Investigations (46-?) and parts of the Theaetetus (201e-210b). Especially in §§ 51-57, I must admit the correspondence is somewhat faint. I annex the revised version of this “synoptic view”, in case it be of use.