Well, we don't know for sure, but, I hope they do. I hope this time, this expansion will have: Sabaoth (Sgt. Kelly/ Animal/ Tank) Guardian of Hell, New Marines, and Sgt. Kelly. MAN, THEY NEED TO RELEASE THE 2ND EXPANSION PACK NOW!
We do know, actually. Thaad even confirmed it, according to Red Dawn17's post.
The license between Id Software and FFG has expired and FFG is no longer allowed to print Doom-related materials. This has been the case for several years now. If FFG intended to renew this license, they would've done it already. The game is dead and done as far as official material goes, you can either accept that or you can spend your own time and emotional distress fervently wishing for something that's not going to happen.
There's still fan-made material, such as Shnar's Advanced Campaign which I, for one, am greatly looking forward to. But that's all. You want a Sabaoth mini, you'll have to make it yourself. (If you actually do this, please be kind enough to share the source parts and a little how-to for the rest of us, as I'd rather enjoy having one, too.) =)