I think it could operate more like in the real world. Instead of the aircraft manufacturers just launching every model and variant, they would issue a press release that they are seeking a partner, a launch customer to launch a model, and they are looking for certain minimum commitment to launch the project.
As far as the interface, it would not have to change. You would have the same order screen, you can place the order. The only thing new would be a check if the order qualifies, if it satisfies the minimum. If it does, the order goes through, and the new press release would be issued (by the manufacturer) that the project is launched, and any new orders from that point on would be accepted.
To add more flavor, maybe the 2nd press release could include the name of the launch customer.