From the Lexicanum:
The Age of Strife, aka the Old Night, was a destructive, anarchic and regressive time period prior to the forming of the Imperium. It followed the Dark Age of Technology, which by all accounts was an age of great prosperity. Depending on sources, the Age of Strife began between M23 and M254 and ended in M30.
From wikipedia:
Dark Future is a 1988 alternate history and post-apocalyptic science-fantasy miniature wargame by Games Workshop. It is set in the then-future year of 1995 (later updating the setting to 2021), in a post-apocalyptic fantasy-inspired alternate reality where the United States of America—as well as the rest of the world—has fell apart. Society has collapsed (almost back to the times of both the Dark Ages and the Wild West—where there's no law and no order), and the natural laws of physics have broke down. Megacorps are now in total control, technology runs rampant, and Sanctioned Ops patrol the roads and highways tracking down and destroying the renegade scum who live there, outside of the law and doing what they please.
Dark future can't really be set in the age of strife is seems