We actually spoke to this today in the Ongoing Black Ops 4 Support section of our studio update thread.

MULTIPLAYER: We know tons of our players love jumping into Nuketown every chance they get, so we’re making the Nuketown playlist permanent starting Nov. 5th! Each week’s showcased Featured Playlist will also grant 2XP on all platforms, so you’ll be able to rank up twice as fast whenever you’d like going forward. We’re bringing a massive list of 2XP Featured Playlists into rotation, and we’ll also be scheduling plenty of special 2X multiplier events and Quad Feeds throughout the year.

Please be sure to check the pinned threads of Reddit or follow us on Twitter for the latest updates.