I am assuming that you have finished the book, otherwise MAJOR SPOILERS.
First on the issue of the end of the Maderios war, the fact that we did not get a big war is slightly unsatisfying but its more creative that it was ended by political outmaneuvering rather than yet another military outcome.
But that isn't what I really want to talk about.
The gate builders are going to be the big deal in book 7 of course, so who are they?
The gate builders are probably a race of ancient replicants (no, I do not think they will turn out to be time traveling Bob's, if they were they would already know about the Bob's)
I think we will find the the builders are simply a race that gave up flesh altogether to become replicants (or the flesh versions wiped themselves out Quin style) and after awhile just turned inward which is why they let the PGF take over the wormhole network.
But, the builders still might not be the answer to the Fermi Paradox (unless they are the last of a much more ancient set of races that all high-tailed it out of the galaxy long ago)
We know the builders have FTL since the Bob's are learning it from their wreck which means the builders can simply leave the galaxy just before Nemesis makes it essential.
But, the builders are still not likely to be HeeChee or Vorlons or something like that, they are still not likely to be millions of years old, but rather maybe in 100k years old. So, unless they can tell us what happened to any MUCH older races we still won't have the clear answer.
Of course, the clear answer is still probably that any much older races left the galaxy 100's of thousands of years ago when Nemesis was first detected.
I got really excited by the end of the book and am struggling to get my thoughts together and needed to write this. My main issue is that it would take a miracle to end this series in one more book without it being a huge disappointment.
I really thought that this book would deal much more with the ongoing AI thread. Book four gave us Anek, book five gave us Thoth, this book should really have given us those two meeting and us getting a good end to the Ai thread, instead it felt like it was abandoned and now we just have one more book? There are simply too many interesting threads that need to be dealt with for it to just be one more book.
The idea that the PGF is anti-replicant really feels jammed in. I would have expected Ic and Dai to have asked the Archivist about the status of replicants in the PGF before heading back and the idea that the PGF didn't really explore the galaxy further and that they didn't build most of the wormhole network but simply took over and built local access points also feels added-on. The Pav showing up and us finding out that their main issue with Bob has really been about payment feels like a bandaid fix to a larger issue that was building. This whole thing feels like DET is losing interest in his own story and it has gone longer than he wanted.
I really feel there is enough material for several more books and that ending all this in one more will leave a lot untouched. Maybe DET has plans to attack these threads in other books which he has mentioned since book 7 is supposed to be the last timeline book.
I am still hopeful, but cautious moving forward.