I wouldn’t necessarily use such grandiose terms but essentially I agree: Motion design might not be THE future but it’ll certainly play a vital role in current and future user interfaces.
It took operating systems and browsers some time to be able to display smooth, seemingly natural animation (using CSS3 animations in the latter case). Now that animation is a staple of modern UI frameworks and operating system UI interfaces it’s only natural for motion to become an important part of UI behaviour:
Motion lends itself to underlining certain actions such as deleting an object or flipping through pages. The swipe pattern from mobile devices has become so ubiquitous everyone who’s used a smartphone before will understand its meaning. Motion tells stories, it adds a perceptible time dimension to a user interface.
Motion allows us to adhere to the feedback principle of UI design. A good user interface should always keep the user informed about her actions and the consequences of those actions. Using animation we can for instance tell the user that her password has been denied by making the password prompt shake (like OS X does).
Moreover, as with other parts of design, crafting your own language for your application’s motion design is crucial for making your application both stand out from the competition and be predictable from the user’s point of view, that is to say the same animation should always convey the same meaning in order to be useful and understandable.