I’m fairly sure that the removal of the T4 models will be because the MY2021 cars are starting to be built.
They will be called B4, and come with mild hybrid technology (not to be confused with electric power in any way)
Power is up by 10 BHP at 197, torque is unchanged, economy is up by a couple of MPG only.
Expect APs to rise when it comes back on the scheme.