Sometimes, when reading certain books, it's important to realize that they were originally published in serialized form. Things like Great Expectations really weren't written to read in a week, so it makes sense that we would consider them long now or make comments about pacing or content that wouldn't apply if we were reading the book serialized.
It's a little strange to think of how people read so many books this way before that we now buy in full volumes. The two different ways of reading are, in some ways, rather opposite, yet does the average reader even know about the issue? When you buy a copy of Great Expectations, it doesn't come with a big note in the front telling you about the change in format.
As "different" as serialization seems to how we read books now, I think we have something similar with the series.
Publication being a business like anything else, making a successful book into a series is one way to keep profits coming. And when readers feel like there are so many options out there yet so little time to sit down with a book, it seems like less of a risk to pick up the sequel of a book you liked than something completely new. So our shelves become full of series.
Originally, Little Women was separate from Good Wives. Now, however, almost everyone publishes them as one book with two sections. Although Tolkien wrote The Lord of the Rings as one epic, it was published in three parts--but you can now buy books that include all three in one. If I don't have anything else to do, I can get through my copy of all the Chronicles of Narnia in a week--as if they were all just one book.
My point is, the way texts are published changes over time, affecting our perceptions of those texts. Will books in a series that we read today as several volumes be published as one piece a century from now? In a hundred years, will students studying teen and YA novels from this era read the whole Twilight or Harry Potter series in one collection? If that seems like too much to cram into one volume, think about how many works are in a single anthology (like one of the Norton ones). The onionskin pages usually include a few books or plays in addition to dozens of short stories and essays and an endless length of poems. If all that can fit into one book, a single series could, too.
I read all of the Twilight material in a couple weeks, Harry Potter in three. Two weeks is a pretty standard amount of time to have to read a book in college, even if it's a Victorian tome (like the originally serialized Great Expectations). So, yes, I think future readers might just be presented with our modern series in single volumes instead of many.
Very strange to ponder.