Yeah 40% seems like a pipedream. I was at a Fortune 500 defense firm and we couldn't get any cloud provider to even offer us anything close to that discount if we agreed to move to them for 3-4 years minimum. That org ended up not migrating because it was significantly cheaper to buy land and build datacenters from scratch than to rent in the cloud.
Defense firms do a lot more than just government work. Also, there are definitely discounts in govcloud when Fortune 500 companies that operate 30+ datacenters start talking to govcloud providers about potentially migrating to their services.