Wada did not mention when that "formal announcement" would take place. E3 is coming up, so it's entirely possible Wada is building up to that, having expressed his hope for an E3 unveil previously. But we've given up on expecting this game to become real any time soon. When it stops existing only in secret trailer form and becomes an actual, playable game, we'll be shocked, regardless of the platform (or platforms).
Update: Wada responded on Twitter (via Andriasang) to speculation about his comments: "It looks like the 'net is heating up. Versus on Xbox? What I said at the earnings press conference was just that until a formal announcement is made at the announcement time, all points about all titles are not finalized." In other words, he is stressing that Square hasn't made any decisions.