Update: It's confirmed
The first details about the 8.4 are starting to appear.
The British TD branch will look like this: Universal Carrier, Alecto, Valentine AT, АТ 2, АТ 7, Gun Carrier Churchill, АТ 8, АТ 15, А39 Tortoise, FV215b(183)
Introducing German light tanks: Pz.I, Pz.I Ausf.С , Pz.II Ausf.G. German light tanks Luchs, Leopard and VK2801 are moved one tier up to tier 4, 5, 6 and rebalanced to fit higher tier.