Background: The US population includes 24 million to 29 million people with diagnosed and undiagnosed chronic obstructive pulmonary disease (COPD). Studies have demonstrated the safety and efficacy of single-inhaler triple therapy (SITT) in reducing COPD exacerbations. Long-term population implications of SITT use have not been quantified. Objectives: This simulation-based projection aimed to estimate the potential impact of widespread SITT use on the US COPD population. Methods: Exacerbation and all-cause mortality reductions reported in the Efficacy and Safety of Triple Therapy in Obstructive Lung Disease trial (ETHOS; NCT02465567) were used to project clinical outcomes in US patients meeting ETHOS trial eligibility criteria (ETHOS-Eligible) and patients meeting a practical definition of SITT eligibility (Expanded ETHOS-Eligible). The US COPD population was modeled with 1000 simulations of patient progression over 10 years. Agent characteristics were based on literature and claims analysis of the 2016-2018 Medicare 100% fee-for-service and IBM MarketScan® databases. Agent annual characteristics reflected incident cases, changes in COPD severity, treatment, mortality, and exacerbations under status quo treatment patterns and scenarios for the adoption of SITT. The scenarios assumed the reduced exacerbation and mortality rates associated with SITT according to ETHOS trial outcomes mean values. Results: Higher than current SITT adoption over 10 years would be expected to substantially reduce COPD exacerbation-associated hospitalizations by 2 million. Applying mean improvements reported in ETHOS for SITT would extend average patient life expectancy 2.2 years for ETHOS-Eligible patients and 1.7 years for Expanded ETHOS-Eligible patients. The number needed to treat to extend the average patient life by 1 year was 8 for the ETHOS-Eligible population and 10 for the Expanded ETHOS-Eligible population. Discussion: Widespread SITT adoption may be impeded by competitive pressures from generic treatments and nonadherence, and efficacy observed in clinical trials may not occur in real-world populations. Conclusions: Assuming ETHOS treatment effects and adherence translate to clinical practice, higher than current use of SITT can substantially reduce COPD exacerbations and hospitalizations and extend survival. These results should be viewed cautiously, because the improved outcomes for SITT in the ETHOS final retrieved vital statistics data were not statistically significant for all comparator therapy groups.