Unmanned aircraft systems (UAS) can be used for scientific, emergency management, and defense missions, among others. The existing federal air regulations, procedures, and technologies do not allow routine UAS access to the National Airspace System (NAS), with the UAS being flown primarily within restricted airspaces. The current Certificate of Waiver of Authorization (COA) process requirement for UAS operations in the NAS are extremely resource intensive, lengthy, and often lacks the flexibility to meet the full mission needs. As the number of UAS operations increases, new methodologies will be needed to enable their safe and routine access to both restricted and unrestricted airspace in the NAS. This paper focuses on gaining a better understanding of growth of NAS usage in near-term NAS UAS demand in that airspace, and an assessment of the impact of unrestricted UAS deployment in the NAS that may facilitate the development of enabling methodologies. Using software simulations for demand growth generation and NAS operations the impact of UAS integration into the NextGen NAS is simulated to analyze its impact on the delay, congestion, loss of separation conflicts, fuel burn, and noise level. Our analyses show that while there is a slight increase in these factors due to additional UAS flight, this increase is minimal compared to the levels caused by the increase of commercial traffic alone.