On the Russian WG Fest stream (at 5:48:46 if the link wouldn't take you there) the devs were talking about the rewards for veterans and said that there will be new rewards this year. While they were talking about the new rewards they showed this teaser on the screen.
If that model under the tarp is not just a red herring then I think the reward this year could be the Object 777 Version II. The vehicle was recently moved down to Tier IX and the shape of the model under the tarp looks really close to the model of the tank. The only thing missing from under the tarp is the AA machine gun. You can see the muzzle brake and the fume extractor on the barrel, the two hatches and the gunner's sight on the turret.