The Major concern is Security and hacking.There may be vital details like Design,costing and new product launches which a manufacturing company wants store in a Cloud.hacking may cause huge losses and drive the company down hill.It is not clear whether administrators of clouds can have over riding access to the clouds they maintain.All problems in an electrical system cannot just be attended by remote.Some times physical presence of engineers may be required for rectification.These are not many in a well maintained system.