For my A Song of Ice and Fire fans out there, io9's been publishing reports that that the long-awaited fifth book in the series, A Dance With Dragons is just five partially-completed chapters from completion. There remains a great deal of speculation that George R.R. Martin's writer's block is permanent, and we'll never see this volume, much less the end of the series. But I'm willing to bet that we'll get at least this book, if not the full series. This is why.
A Dance with Dragons is hugely overdue. The HBO adaptation of A Game of Thrones is an enormous marketing opportunity, both to reignite the excitement of long-standing but frustrated fans of the series, and to introduce a new generation of fans to the series who might be wary of starting into a new universe without guarantee that it is or will be completed. If Martin misses this opportunity, Del Ray might decide to walk away from the series as a whole, or to demand the return of the advance for A Dance With Dragons (they might even try to recover more than that, on the grounds that Martin's in breach of his contract to deliver a completed series). This is the most concentrated commercial pressure Martin could possibly be under. And his agent died recently, leaving him without an experienced, credible advocate to argue for more time for him.
One interesting challenge, though? Even with those five chapters incomplete, the manuscript's also at the limits of what Del Ray can publish in a single volume, size-wise. I don't know if that means we might be forced into an 8-volume series, or whether we'll just get a longer subsequent book (if we get one at all). But if they're thinking about publication details, I think that's a good sign, even if it means tricky logistics.