I remember reading research on this from years back but I'm sure it holds good for today.
It said a CPU has a safe life expectancy of 10 yrs but overclocking can reduce this to 7 years. We can forget about keeping a CPU for 7 years so the question about durability is not an issue, unless you use extreme loads and don't cool the CPU properly or drop test your system box from a great height after a bad trade.