Note: my question is specifically about whether this series had a conclusion or not. Not publisher decisions about optimal book length. I was aware of those already.
I've read The Risen Empire and The Killing of Worlds by Scott Westerfeld. If I recall correctly, the second book ended with the Navy Captain back on one of the imperial worlds, near his romantic interest, during some kind of big public celebration. Nothing really came to a conclusion.
Had some really good ship-to-ship combat sequences, much more inventive than the average dreadnoughts-in-space fodder we usually get. Think more chess-game type of stuff, with relativistic speed grains of sand and a fighter pilot linked into a minuscule recon drone, a la Accelerando.
Plus some intense spying bits.
But, never heard of it concluding. I almost bought another book in the series, but then realized that, rather than being book #3, it was book #1 and #2 together.
He seems to have written a lot of other stuff since, so am I correct in thinking he's just found more lucrative outlets than hard Mil SF?
P.S. is there a tag for has-this-series-ended?