Don't get me wrong: I'm a Beatles guy; if given the choice to listen to the Beatles or Dylan (or any other artist for that matter) for the rest of my life to the exclusion of all other music, I would choose the Beatles every time. However, this isn't about personal preference; this is about an objective stance on which artist will be seen to have greater historical importance in the distant future.
One thing that is fascinating about Dylan and his association with rock music is how little of his overall body of work can truly be considered 'rock'. Ultimately, his contributions to the genre are confined to just three albums: Bringing it All Back Home, Highway 61 Revisited, and Blonde on Blonde. If you think about it, very little of Dylan's work that followed this can be clearly defined as 'rock'. After all, his greatest work subsequent to these albums is Blood on the Tracks; is that a rock album? Folk? Something else entirely?
What is fascinating with Dylan's brief dalliance with rock is that, in those three albums, he managed to virtually redefine the genre. It was those three albums (along with the work of The Beatles and the Rolling Stones) that would, ultimately, transform the genre of 'Rock N' Roll', a popular kind of dance music from the mid-1950's, into Rock music; they elevated the genre from music that was meant to be danced to into music that was meant to be listened to.
However, his influence on the genre as a musical form is not the sole reason that he will be the one who ultimately transcends the genre; after all, The Beatles and the Stones (and, arguably, many other artists who emerged in the mid-late sixties) had just as much, if not more, to do with this evolution as Dylan. It is the same reason he is being awarded the Nobel prize for literature, not music. As this article from the Atlantic points out, he is being awarded as a songwriter and not as a musician. The focus is upon the songs that he wrote and not his performance of those songs. After all, Bob Dylan is the poster child of the songwriter whose own voice is an acquired taste. In fact, before he had even established an identity as a performer in his own right, his songs--- performed by other artist--- had become part of the popular consciousness.
The genius of Dylan as a lyricist is that his words manage to be both reflections of the time in which they were written while still being ambiguous enough to remain universal and relevant five decades later. Even the so-called 'topical' songs of his 'protest' era are capable of working just as well (perhaps even better) when they are removed from their original context.
So, I think it's pretty safe to say if I were to cryogenically freeze myself for a few hundred years that, when I awoke, people would still know Bob Dylan's work even if they'd long forgotten about rock and other popular music of the mid-twentieth century. And I take comfort in that.... however, personally, I'm really hoping I'll also still have access to Rubber Soul.
I'll leave you with what I have always felt was Dylan's greatest 'rock' moment: