system
Given the following post, respond as if you're commenting on Reddit:
human
[Dune]The events of Dune never happen so the Galaxy continues on fairly peacefully. The Guild has a monopoly on space travel, if they decided to use that control tactically is there any reasonable likelihood that they could fail to conquer humanity?

Many worlds rely on importations of resources, if those imports stop those worlds descended anarchy. You can't project military force on anyone else without a spaceship and the guild has all the spaceships.  Sure, the guild might not have an army yet, but they can probably get quite a few to agree to fight for them under these circumstances and they do not need a vast army, no one else is able to project any force at all.

It might take a while, but would there be any effective strategy to stop the Guild deciding to just starve out or isolate all aspects of civilization which reused to kneel before it?


Obviously they need spice, but stockpiles exists on many worlds and presumably they could eventually marshall the resources to take an isolated Arrakis anyway.
gpt
They need a lot more spice than you'd think.  Navigators live, eat, and breathe spice.  They won't willingly do anything that threatens their supply, and cutting off transport would do exactly that.  

Whichever family was currently running Arrakis would cut them off instantly and threaten to destroy the spice fields, and the Navigators would surrender.  After that, the Great Houses would impose sanctions against them, probably in the form of reduced allotments of spice.  They know that, so they will never make that move.

The spice must flow.