That would be the worst business decision on the planet.
You promise a game that everyone has been looking forward to for years, and then don't deliver on it? How would the customer base react to a business that pulled a stunt like that? Especially a customer base of multimillions of people, with a business as high-profile as Nintendo, selling a product as well-known as Pokémon games?
No company could intentionally lie about something as big as that, something as hyped and expected as that, and then not deliver. The customer base will be furious with them, will boycott their products, will never trust them again. There's also a good chance such a stunt would fall under the category of "false advertising," which is illegal and which companies can get sued for, and can lose a lot of money over.
They would have to be seriously retarded to do something like that, which they are not. Remember that this is a company run by adults that think about the consequence of actions like that.