You won't be able to play DMZ on the new Urzikstan map or any other new Warzone map. It won't count toward progression, either. Previously, the DMZ was one of the best ways to gain XP.
Rather than Chechnya, the game largely takes place in Urzikstan which is also located in the Caucasus, was invaded by Russia in the 90s and features clashing between secular nationalists and Islamists. Furthermore, Urzikstan's flag closely resembles the Republic of Ichkeria's.