I've been pestering Google about this for a while and Google gave me a statement yesterday afternoon saying it ain't going to happen this year. Google told me:
With the holidays upon us, it looks like the penguins won't march until next year.
Of course, Google wanted to release it this year but as Gary Illyes said, they wouldn't if it was unfinished and I guess unfinished it is as Google said, it won't be happening this year.
John Mueller also confirmed this on Twitter, if you don't take my word for it:
Webmasters and SEOs who were hit by Penguin 3.0 are eager for the new version, hoping they performed enough of a clean up to warrant ranking again in Google. The new Penguin 4.0 update is expected to be a real time Penguin algorithm - meaning, webmasters won't have to wait for algorithm pushes or manual data refreshes to fix the issues but rather just wait for a recrawl of the links.
So that means we won't have any Penguin refresh or update for about 14 months since Penguin 3.0. The truth is, we did see Penguin shuffles throughout last year through December 11, 2014 which means its currently just under a year since any Penguin activity at all, but it will be over a year because nothing will be changing until 2016.
As always, I will keep you posted on Penguin and all Google algorithmic changes as I spot them.