Today the aviation industry is witnessing a paradigm shift in the propulsion technology which has been unseen since the 1930s, when the gas turbine took over from the more established piston engines. For the emerging electric propulsion to survive and flourish, it must demonstrate clear superiority over the mature baseline technology of the gas turbine. It is a fact that the current battery technology is a limiting factor as it is not competitive compared to a gas turbine that is 30-50 times more energy dense. Naturally, the present electric propulsion developments concentrate on smaller aircraft applications and use on a large aircraft is possibly decades away. Apart from the energy density, from a thermal perspective the architectures are vastly different from each other. A conventional aircraft fitted with a gas turbine has readily available heat sinks in fuel and air that aids in heat transfer. Compressed air bleeds from the engine manage the thermal demands of the engine itself plus the aircraft systems. On the other hand, a battery-based aircraft does not have this advantage and therefore must deploy dedicated thermal management systems for cooling and heating demands, and that drains energy from the battery. This paper summarizes a study of the Electric Propulsion Systems’ (EPS) Technology Readiness Level (TRL), a Theory of Inventive Problem Solving (TRIZ) trends of engineering system evolution, comparison with conventional aircraft/gas turbine configuration including their thermal management systems, and the impacts on type certification regulations. TRL shows hybrid-electric leads as a bridge between gas turbines and electric systems, followed by electric only propulsion due to slower battery technology breakthroughs, while distributed propulsion lags due to novel airframe and thermal challenges. TRIZ analysis suggests that integrating self-cooling, structural composite batteries, and distributed propulsion with intelligent thermal management can propel EPS to new heights. A comparison of the propulsion systems showed that the thermal management and materials selection will be the key focus areas. The regulatory authorities are adapting the airworthiness regulations to the ongoing changes, and more regulatory evolution is likely to keep up with these technological trends.