As reported last June, Lynch has decided to deliver three novellas before releasing the next full novel in the series, The Thorn of Emberlain (which itself exists as a full draft). The first of the novellas is now called More Than Fools Fill Graves, and will be followed by The Mad Baron's Mechanical Attic and The Choir of Knives (the latter two titles have been known for well over a decade by this point, although might still be subject to change).
The three novellas form a continuous but optional narrative, starting the moment The Republic of Thieves ends and continuing through to the start of The Thorn of Emberlain. The combined length of the three novellas will be around three-quarters of a typical Gentleman Bastard novel.
We don't have any kind of release schedule for the novellas and the following novel yet, but hopefully news on that will follow soon now that the first novella is both complete and titled up.