system
Given the following post, respond as if you're commenting on Reddit:
human
[40k] What might the galaxy be like if the Horus Heresy hadn't happened, or had been crushed swiftly?

Suppose the Heresy is either entirely averted, or is crushed swiftly and with minimal losses. What's the galaxy like for the next ten millenia and beyond?
gpt
The Emperor doesn't spend the next 10,000 years as a rotting corpse on the Golden Throne and isn't falsely deified by the Imperial Cult.  The Imperial Webway is completed without issue, meaning that the IoM can completely avoid Warp travel.  The Space Marine Legions are not broken into smaller Chapters with smaller numbers.