how long will it last

My current build from March 2015 is still using the same RM650 PSU from Corsair, with no issues such as shutdowns etc. My components are Strix 970 @ 1491MHz, FX 8350 @ 4.0 GHz, 14GB RAM, NH-D15 and 3 x 140mm case fans. I measured power consumption and at idle the system pulls 120-140W and under...