NX8's came out in 2018 IRRC
Nightforce has a history of sitting on models for quite some time before updating or replacing. If I were a betting man, I'd say we'll see a new ATACR II sometime around... northwest Florida getting a bunch of snow, oh wait, we just got 8" in Navarre!!! (felt like I was back on the farm in Colorado), so I'll update that with "hell freezing over"...
The 4-20 was a strange offering that was thrown in a couple years ago, why they'd limit the low mag FOV vs. the 4-16x42??? thus leaving the 4-16x42 as my favorite ATACR to date for gas gun and crossover use.