Considering how the rate of updates has slowed, and Ashley's scarceness on the forums (except to deal with bugs), I would imagine that C3 is under heavy development at this point. Course, holidays might not be the best time to reveal the future successor to your current product.
I'll lay my money on early 2016 for the reveal, with early adopter following a few months later.
I hope it's gonna be good and streamlined. Hopefully backwards compatible and with fixed issues from c2. And then I'll be an early adopter.