HTC, during an AMAA (ask me almost anything) session on Reddit, revealed that the company did want to update the One X to Android 4.4 KitKat. However, plans for the same were scrapped as the Tegra 3 equipped global variant would have been left out from receiving the same. HTC blames NVIDIA for their poor support (Tegra T33 and T37 SoCs used in the HTC One X and One X+ respectively), which is the reason that the company had to scrap KitKat upgrade plans for their 2012 flagships.
The HTC One X in the US runs on a Qualcomm Snapdragon chipset. An update could certainly have been worked out for the device, but international One X owners would feel bad (leading to a possible backlash) if HTC were to proceed. Thankfully, the session ended on a positive note.
"We're now actively exploring how we can make the jump to 4.4."