Futuristic military submarines are likely to integrate cutting-edge technologies to enhance stealth, endurance, lethality, and survivability. Here are some features we might anticipate in a futuristic U.S. military submarine:

1. Advanced Propulsion Systems: Incorporation of quieter and more efficient propulsion systems, such as advanced electric propulsion or possibly even hydrogen fuel cells.

2. Improved Stealth and Signature Reduction: Integration of advanced stealth technologies to reduce acoustic, electromagnetic, and hydrodynamic signatures, making the submarine harder to detect by adversaries.

3. Autonomous Operations: Enhanced automation and autonomy for various submarine operations, including navigation, surveillance, and possibly even autonomous decision-making in certain scenarios.

4. Next-Generation Sensors: Integration of advanced sensor suites, including sonar, radar, and periscopes, with improved range, sensitivity, and processing capabilities to detect and track targets more effectively.

5. Directed Energy Weapons: Potential deployment of directed energy weapons, such as laser or electromagnetic railgun systems, for defensive purposes against threats like missiles and torpedoes.

6. Underwater Unmanned Vehicles (UUVs): Deployment of UUVs for various missions, including reconnaissance, mine countermeasures, and even offensive operations, extending the submarine’s operational reach and capabilities.

7. Enhanced Communication Systems: Integration of advanced communication systems for improved connectivity with other naval assets and command structures, enabling real-time data sharing and coordinated operations.

8. Modular Design: Utilization of a modular design approach to facilitate easier upgrades, maintenance, and adaptation to evolving mission requirements and technological advancements.

9. Enhanced Crew Comfort and Habitability: Implementation of improved living conditions and amenities for crew members, including better ventilation, lighting, and recreational facilities, to enhance crew morale and performance during long deployments.

10. Environmental Adaptability: Incorporation of technologies to enable submarines to operate in extreme environmental conditions, such as under polar ice caps or in deep-sea regions, expanding their operational flexibility.

These features represent just a glimpse of what could be possible in a futuristic U.S. military submarine.
The actual design and capabilities would likely be shaped by a combination of technological innovation, strategic priorities, and budget constraints.