The National Intelligence Council look at the European future was part of a study on global trends done every four years, the EU Observer reported.
The NIC predicted that the union will have successfully carried out institutional reforms by 2025. But it said there would still be a "democracy gap" between the citizens of the member countries and the bureaucrats in Brussels.
Analysts said they do not expect Europe to be a major military power on a global scale.
"Continued failure to convince skeptical publics of the benefits of deeper economic, political, and social integration ... could leave the EU a hobbled giant distracted by internal bickering and competing national agendas, and less able to translate its economic clout into global influence," the authors said.