I'm wondering if they just didn't obtain licensing to produce a Mirage/Dino toy... or weren't willing to pay the price being asked. After all, they have to give a percentage of every Movie toy to Bay, plus pay for licensing to GM, Lockheed and Saleen, and probably Mercedes now too.
With no sign or mention from Hasbro of a convertible Mirage toy after all this time that the movie has been out, it just makes me feel like they decided against doing one at all.