The audience would be fans of the author and the occasional, dead cat. If the writer has somewhat of a name it might work. It will work better if the author plans to produce more than one, 1-4 page PDF, or the publisher/producer plans to enlist other well known authors and create a line of sorts. A sale might lead to sales.
As far as what the product would be, I have no idea. Whatever It was, it would have to be good. Nobody want's to pay $2 for four pages, and think to themselves afterward, "What was I thinking? It was only four pages!"
Though... I recently reviewed Strange Stars by Trey Causey. It's 32 pages at 10 bucks. The production value is excellent, the writing is decent, but it's a splat book, not as it is subtitled a "Setting Book." It has some good ideas and as I said very nice art, but if you bought it thinking you were going to get, or even hoped to get a setting "treatment" (given it's 32 pages and accomplishing a setting would be difficult) you might be sorely disappointed. After I read through I was compelled to give the reviews over at drivethru a read... And to my surprise most of them were very positive. I'm aware Trey has a following of sorts so yeah, In order of importance:
Author
Production Value
Content
And just to be clear, the order of this isn't what I would want it to be. In fact, you could flip the list on its head and that would be my preference.