If the threads were that badly damaged...doubt that a Ford tech would of re-installed a new plug and torqued it to spec.. you should be good to go for another 100K miles. I would check to ensure it's staying tight from time to time.
08 FX4... Flowmaster Exhaust, line-X, Sky Jacker leveling kit. 295/65/20 Nitto trails mounted on 20 X 9 Carroll Shelby wheels. AIRAID CAI. Harley headlamps and LED Tails & 3rd brake lights,custom upper and lower Grill. Edge Evolution. Interior/Exterior LED lighting, NFAB step bars, America Tri-fold Tonneau cover.