Well, if his previous Quirke novels are any indication, we can expect a richly detailed setting, likely in Dublin. The characters will probably be morally ambiguous, as is often the case in his works. There might be a complex web of relationships and a mystery that slowly unfolds over the course of the story. His writing style, which is often atmospheric and brooding, will likely be maintained. He might also introduce new elements to keep the series fresh, perhaps a new type of crime or a different social aspect of the time period to explore.
Since Benjamin Black has a certain style in his Quirke novels, we could anticipate a continuation of his dark and moody tone. The next novel might delve further into Quirke's personal life, perhaps his past traumas or his evolving relationships. In terms of the plot, it could involve a more convoluted mystery that challenges the readers to piece together the clues. Also, given the historical context of his previous works, we may see more of the cultural and social nuances of the era, which adds depth to the overall story.
Maybe more complex characters and a deeper exploration of the mystery genre that his Quirke novels are known for.