Compound semiconductor mid-wavelength infrared photodetectors operating at room temperature are the sensors of choice for demanding applications such as thermal imaging, heat-seeking, and spectroscopy. However, those detectors suffer from high dark current and thus normally require additional cooling accessories. In this work, we argue for the fundamental feasibility that by using nanowires coupled with plasmonic nano-antennae as photoabsorbers, the dark current can be largely reduced compared with typical planar devices. To demonstrate the idea, we simulate the device characteristics, such as dark current, responsivity, and detectivity, of InAsSb0.07 nanowire photodetectors, and compare those properties with the best research InAs photovoltaic diodes. The results show that the designed nanowire detectors offer over one-order lower dark current and enable a peak detectivity of 7.0×1010 cm Hz1/2W-1 at 3.5 μm. We believe this work will provide a guidance to the design of nanowire-based MWIR photodetectors and stimulate additional experimental and theoretical research studies.