I was trying to enhance the image to see more details, and I think for the first time ever we may very well be getting the "other" Sandtrooper gun. It's an MG-15 with ammo drums, and the stock removed. It was basically the gun mounted in some German airplanes in WW2... notably, the Stuka Dive Bomber had a rear-facing one.
I've asked Hasbro on this weapon specifically in the Q&A,
maybe they're gonna deliver it. The other option I came up with is it's the Spacetrooper's blaster rifle, which is cool, being re-used in maybe a simple black deco. It's tough to tell though.

Wookiepedia has an article on the gun I think it might be though, which I guess it got a designation from LFL finally, after all these years.
It's not easily seen in the movies which makes it kind of lame that the Wookiepedia article claims it as the "preferred weapon of Sandtroopers". I'd say that's inaccurate. Then again it's Wookiepedia, so whatever.
Anyway, I'm gonna go on a limb and say first that I THINK this Sandtrooper comes with a spiffy new blaster. We'll see. I hope he does because I really would like two of these at least, maybe more. Three may be worth the $$$. I just hope they're a fair price.