>>529424583
>That's probably not canon, but even without warp travel of any kind, humans would definitely survive in isolated pockets.
Without Astronomican it would be extremely tough and most of the worlds wouldn't survive, especially those whose vital supplies depend from others planets. Imperium would fall apart for sure.
And yeah, It'd be way worse than age of strife, because at least before rebellion there were no all mighty daemon primarchs deliberately trying to nuke everything loyal to the Imperium.