Narcissists can be good at making future promises with no intention of fullfilling them. They do this to get you to do what they want you to. They will have you jumping through their hoops and fulfilling their needs in your hope that the narcissist will give you what you want, but they won't.
Future faking is a method of narcissism that gives the narcissist's target something to look forward to something in the future if the target agrees to what the narcissist is asking for. It's just another type of false promises.