If memory serves, Blitzkrieg was an experiment to gauge sales interest in longer BT stories. Also, stories of that length take time to conceive, write, revise, fact-check, revise (again), copyedit, revise (sometimes), and typeset. Based on the "experiment" model, there would need to be time to evaluate the success of the initial offerings before greenlighting any future installments, which would mean a sizable time gap between the publication of the initial test-run batch and any further offerings. In other words, if Blitzkrieg DOES continue—and I honestly don't know one way or the other, as that's well above my pay grade :D—I'd assume any further stories are probably still in one of the aforementioned stages.
Hopefully we'll hear something one way or another in the near future. Until then, I'd keep my fingers crossed. More BT fiction is always a good thing, regardless of what form it comes in ;D