How was it made with a new forme in mind? Think about it - Kyurem represents wuju, which is the absence of Yin and Yang and absolute zero, which is the absence of heat. Thus, Kyurem's design makes perfect sense when you think of it like that and how it relates to Reshiram and Zekrom - Reshiram has the element of Fire which is an ancient symbol of life. Zekrom has the element of electricity, which is a modern symbol of life. Both have the power to give us energy (thus life) and to destroy - like how each individual human has yin and yang. Kyurem, being wuju, has no yin and yang - thus, no energy.
Also, if Kyurem was designed to have an alternate forme, why was it not programmed into Black and White? After all, Meloetta will be released after Grey, so why was Meloetta's other forms included in BW but not Kyurem's? The "Because Kyurem is a version mascot and Meloetta isn't" argument is silly and without foundation - after all, Shaymin wasn't a version mascot and its Sky forme was excluded from Diamond and Pearl - same with Rotom and its forms. GameFreak including Meloetta's Pirouette forme in Black and White is obviously them trying to avoid the compatibility problems that plagued Diamond, Pearl and PBR.