SocProf reviewed The trade of queens by Charles Stross (Book six of The merchant princes)
Review of 'The trade of queens' on 'Goodreads'
4 stars
It does not look like this is the end of this series. Too many loose threads.
Also, conservative readers seem to be upset about the very obvious insertion of Bush / Cheney / Rumsfeld in the story. Read the Amazon reviews and you'll get a good sample of "shut up and write sci-fi."
However, the last two volumes have been all over the place and it's not clear Stross knows where he's going with all this.
The series has enough materials to continue (and I can't figure out why HBO has not created a series based on this) but if this is the end of it, it's very unsatisfying.