Let the mockery begin. I’m a 35-year-old man who read and enjoyed New Moon. I remember when the Harry Potter books first came out I took a lot of heat for reading those too. But look at how big that franchise eventually became. Everyone eventually read the books and saw the movies. Even though the series was first marketed to younger readers, it eventually reached readers of all ages.
I’m not saying the Twilight Saga is anywhere near a good as the Harry Potter stories nor do I believe that they will reach as broad an audience, but I do think a lot of people will eventually end up reading these books. If for no other reason than to see what all of the hype is about. If you’re into D&D then you might actually enjoy these books more than you expect.