Some of the ideas in the pipeline for high-altitude launch to orbit vehicles and hybrid vehicles employing scramjets may exceed this. Assuming the current arc

Some of the ideas in the pipeline for high-altitude launch to orbit vehicles and hybrid vehicles employing scramjets may exceed this. Assuming the current arc toward private advance aerospace projects continues, I wouldn't be surprised to see things like sub-orbital passenger flights that exceed that speed. (Edit: that last may depend on what the precise definition of "entirely within the atmosphere" is).