Yes, but it's less than half the active rolling stock. 538 vs 648 of the 7000 series, and and there are still 100 more 7000 series cars yet to arrive, which will lead to more retirement of the older cars. Once the 8000 series starts arriving in 2024, the end of carpeted trains (which will by then be...I dunno, less than a third of the cars?) will be very near.

Numbers: https://en.wikipedia.org/wiki/Washington_Metro_rolling_stock