I wish I could share your collective confidence that despite the odds on Corbyn never being PM he won't be able to cause chaos through the Unions.
And with no 'wars' on and large scale military deployments (I'm talking HERRICK style and size) I can see the military being drawn into various MACP scenarios to keep the country running when the Unions walk out. Corbyn+Unions+SNP is a frightening prospect for any fair minded person in their right minds.