Level-5 registered a trademark for Professor Layton and the Unwound Future lately, which suggests that this could be the English equivalent to Professor Layton and the Lost Time Travel. Nothing has been confirmed yet, but with E3 just around the corner, Professor Layton and the Unwound Future could be on store shelves before Christmas.
I thought the RPG was part of the Professor Layton and the Spectre's Flute (or whatever it will be called.)