Employees on the 'floor' must overcome their resistance to management, and allow more of their 'ranks' to become part of the managerial side of things, without feeling betrayed by their fellow laborers. Improving communications

Regular, face-to-face meetings with both managers and workers are essential to improve company relations. This would insure information is given in a timely fashion, and if there is any error or real problem, it can be dealt with immediate with constructive feedback, rather than left to fester like a sore. Giving a top floor employee higher managerial status, but still employing him 'on the floor' to act as a mediator would be an excellent idea. John, for example, still speaks the language of the employees could be used as a facilitator. This will increase and improve the flow of feedback and information between the shop floor and management. Mandating that all managers...

A gesture of trust would be to create common company spaces, where all employees can meet, talk, and interact. Giving special perks for management is counterproductive, and looks patronizing, like allowing teachers the use of a special 'faculty bathroom' during school hours. This will also work to create a common workplace culture.
Some formal conflict mediation may be required to create a truly integrated organization, given the current relationship between Greg and John. Bringing in someone from the outside, without workplace culture 'baggage' to act as a labor-manager mediator might be helpful to broaching differences and creating a more effective workplace language, organizational goal, and exchange of information between all workers.