Just finished the third book in the trilogy…
I have just finished reading The Victorious Opposition and I am about to purchase the next in the series, Return Engagement, which has just been published in the USA and available in the UK from Amazon.
You can purchase the UK edition in October (which has a much better cover in my opinion).
I am a bit of a fan of Turtledove, but didn’t enjoy American Empire as much as previous books until I read the final part of the trilogy which was very exciting and riveting. Glad in one way I left it a bit before I read it, as I have not needed to wait for the start of the sequel trilogy.