Square Enix has registered the name Monster Battle Road with the US Patent Office on June 23rd. In Dragon Quest VIII, a player could capture certain monsters and assemble them into teams of three. These teams could then be used to fight other monsters in the Monster Battle Road to win prizes.
It is still unknown why Square Enix has decided to register the name of the minigame. It is possible that Monster Battle Road will be added to upcoming games with stronger emphasis. Then again, given the number of Monster-titled spin-offs in the Dragon Quest series, Monster Battle Road could very well appear as an independent game. Perhaps it will be the US release of Dragon Quest Monsters: Joker.
Square Enix has also published the subtitle of Front Mission 5, Scars of the War, for opposition. This would indicate that a US release is still on the way.