I'm not trying to imply that attention spans aren't shrinking. I don't know if they are.
That said, more often then not, I don't finish an article because its crap content-wise, or because someone decided they don't know how paragraphs work and made it one huge block, or someone needed to meet a word count requirement, or thought they could amp up the prestigious by going long-form without the meat to back it up.
I love that everyone is a content creator, but I don't have to give a bunch of mediocre blog posts on lifehacker the same attention I give to a James Joyce novel. I consider that an advantage not a problem.