Li-ion batteries (LIBs) are among the most advanced technologies for energy storage. Due to the potential criticality of lithium raw materials, Na-ion batteries (NIBs) are frequently suggested as a low-cost, environmentally benign alternative to eventually complement or even replace LIBs. Herein, we present a holistic modeling framework to assess the potential of NIB cells from a performance, cost, and environmental impact perspective. To this end, we employ a physics-based battery cell model to project practical specific energies of LIB and NIB cells subjected to varying discharge rates. The derived performance metrics are subsequently used to parameterize a bottom-up battery cell cost model and to assess life cycle greenhouse gas (GHG) emission. Benchmarking model results obtained for NIBs (NaNi1/3Co1/3Mn1/3O2 vs. hard carbon) against state-of-the-art LIBs (LiNi1/3Co1/3Mn1/3O2 vs. graphite), we find that NIBs made from currently available active materials cannot compete with LIBs in terms of performance, costs, and environmental impact. Identifying battery performance as a key parameter driving manufacturing costs and GHG emissions, we argue that in order to make NIBs competitive to LIBs, one of the main priorities of NIB research should be the development of anode and cathode materials offering specific charges, voltages, and cycle life times comparable to or higher than for LIB active materials.