No, when an EX card is released in Japan as part of a theme deck it NEVER gets a full art version, look at Moltres and Articuno EX from Plasma Storm.
I think Poke Tactics was referencing the Full Metal Dialga that was, indeed, a Secret Card released in roughly 1/6 Hyper Metal Chain Decks in Japan. To date, it's the only time there's been an SR given out in some Japanese theme decks. It certainly could happen again, but since it's a "secret" there's no way to know until after the deck comes out later this month.
I don't really think it's likely to happen, but it's not impossible either.