Through model simulations, we projected and analyzed potential long-term (50 year) effects of repeated fuels reduction treatments on forest structure, species composition, wildfire behavior and bark beetle-caused mortality in a 44,000-acre landscape in the Blue Mountains of northeastern Oregon encompassing a wildland-urban interface. The study area is representative of many Western areas targeted for treatments to reduce the risk of severe wildfire and restore forest structure and natural fire regimes. We used modeling tools to simulate forest dynamics and potential disturbance impacts, including a distance-independent, tree level forest vegetation simulator and wildfire behavior and bark beetle risk models. Over time, model outcomes suggested that thinning large areas of landscape could significantly alter wildfire behavior, especially propensity for crown fires. Mortality from crown torching, however, was projected to remain significant due to regeneration triggered by thinning and residual fuels. Scenarios that simulated single rather than repeated treatments showed little potential for change in wildfire behavior over time. Projections suggested that thinning treatments may alter forest structure primarily by reducing multi-story old forest and stem exclusion structures. Predicted outcomes of thinning included a general shift to early seral species, because algorithms targeted removal of late seral species. Projected changes in bark beetle-caused mortality risk from fuels treatments varied among species examined. The simulations demonstrated the complexity and long-term challenges of managing conifer densities and forest fuels in areas like this, and motivated discussions about possible alternative methods to control densities by manipulating mortality in the pre-seedling phase of the conifer life cycle.