This may be a trend for some, but certainly not for others. For some people vintage is a lifestyle thing that has little to do w/ where mainstream fashion is going. Of course, what this "means" is as individual as the person choosing to wear it. Methinks there's a direct (and perhaps negative) reaction to fashion's offerings in recent years that's driving much of it. I'm not so sure this is a trend in the truest sense either or that it's going away.
I definitely think that there's many undercurrents here, but let me just deal w/ one. Frankly not all fashion compliments all body shapes, so what do you do if you don't have the body that's currently "in"? Do you choose to wear what's in even if you look badly in it? Do you go vintage, make up your own look, etc? Given that there's so many choices out there and that the dictates of fashion are a lot less powerful than they once were...the sky's the limit. You're free to create your own look w/o really worrying about what mag X says is THE look for fall.