so that will likely mean that the next order of cvars following the 7000s will have to be jumped to the 9000-series sequence numbers, translation: 9000 cars-9K, Type #8 Cars, rather than 8K type #8, since the 8K sequence is taken by recycled Type #1 Cars
WMATA might end using a numbering schema similar to the schema used to number busses.
Method to the Madness: WMATA Bus Numbering
My guess is the 8k cars will be retired and replaced by other cars in the fleet that will allow 8000 to be used for the next series after 7000. The cars that will replace the 8k cars will likely be renumber upwards within the existing numbering schema. (As an example 2XXX cars would be renumbered 25XX)
The 7 k cars are going to be procured in 4 production blocks much like the Breda cars were. However I don't WMATA will span the numbering the same way.
1st block of 126 cars 7000-7125
2nd block of 130 cars 7200-7329
3rd block of 300 cars 7400-7799
4th block of 90 cars 7800-7889
John in the sand box of Maryland's eastern shore.