I've also just completed writing the 4th book and it turned out to be a whopper. It's a much longer story than I had anticipated and couldn't be constrained to a novella. So I've now written the first full-length novel in the series and expect that the remaining books will also be novels.
Now that I'm basically halfway through the series, I plan to take a short break to finish up Death Moon. Rogue Hunter fans have waited long enough for the sequel to Valor and I need to deliver it ASAP.
I'll be back with another update soon. Look out for it.