The next branch in the game will be the American Heavy Tank line named Yoh. Let's see what they are about.
They were introduced to WoT Blitz this summer and they feature the "Reserve track" mechanic on both platforms.
Movement
The mechanic is unique to this line. What it is all about is simole: you get 2 sets of Reserve tracks, one for each side. If your main track gets destroyed, you can still move, but with a 30% speed penalty. If your other main track is destroyed, another 30% penalty applies. To immobilise the tank, you need to destroy one main track AND its corresponding reserve track.
Repairs
If you're immobilised, the reserve track will be repaired first, then the main track. If you don't wait and start moving with the reserve track, the 30% speed penalty applies. Repair of the main track starts once the reserve track's repair is complete. Most probably repair times will be different (lower for the main track). Repair kits will repair both type of tracks at once. Repair speed can be increases for both types in the normal way.
Counterplay
At first immobilising a Yoh tank seem helluva job. It isn't quite. Since both tracks are held by the drive wheel, shooting at it will destroy both tracks. Module damage must be high enough, tho. Explosions from HE shells (from arty, mainly) can also destroy both tracks at once.
Transition
The line starts at T6 as follows:
-T6: Pawlack tank – DOES NOT have the Reserve track mechanic.
-T7: M-II-Y – starting from this, every tank in the line has the mechanic.
-T8: M-III-Y
-T9: M-VI-Y
-T10: M-V-Y (60th Tech Tree T10 tank, btw)
-And the obligatory Premium tank, the T8 M-IV-Y, has the new mechanic.
ETA: first half next year
Source: https://www.reddit.com/r/WorldofTanks/comments/qweq55/yoh_lets_talk_about_the_new_murican_tanks/