So, the upcoming Grille 15 will be available to the supertesters following the upcoming patch and if all goes well (like it always does *coughs*), it should be introduced in patch 9.15.
The 9.14 patch itself is planned for release for late February or early March. There’s not much information about premium tanks or features out there for this patch, but surely more will come soon.
The Object 244, a Soviet tier VI premium tank is also planned to appear on sale. It’s planned to cost 5500 gold or if you’re lucky (or just determined) you can get one in events or personal missions.
Also, the German Bulldog tank, who appeared on the supertest server seems to be better than its American counterpart. Some people argue that the tank is overpowered, but there’s a lot of room for nerfs.