What do I imagine selling a series would require?
Most of the stories I write are intended to be part of a series. It's not unusual for the original concept to actually be a book 2 or the final book. Long before I draft any manuscript in the series, I've a blurb in mind for what happens in the other books in the series.
Yes, yes, I am one of those writers who believes a series should have
a definite end and constantly work towards that end.
The blurbs aren't that long -- no more than 250 words, a one-sheet, if you will. They include a summary statement for each of the following: the Setting, the Primary Cast, the Goal, the Motivation, the External Conflict, the Internal Conflict, and the Resolution. I write those to aid me with seeding and maintaining the cart-horse-carrot order of events while I write the series.
I imagine other people on Team Buy KAK's Books would like those one-sheets to ... you know ... pre-sell the series to people who might want to pay for said series.
Imagination. It's a wonderful thing.
However, to sort fact from fiction, ~snort~ I defer to the rest of my fellow Word Whores who have actually sold series. I'm as interested in the actual deliverable as you, my darling readers.