Presumably you'd replace the chip due to speed long before you'd ever hit its EOL.
I overclocked my i7-4790k from 4.0 to 4.7 GHz just using the "easy" button in my ASUS software and called it a day. It's been humming happily along for 24/7 since the chip came out.
mmm people with sandybridge still chugging along. I'd say pentium 4 is now near EOL. Core 2 is still pretty good. I'd say only big addition was AVX/AVX2 on sandybridge/haswell which gave us YMM registers.
I overclocked my i7-4790k from 4.0 to 4.7 GHz just using the "easy" button in my ASUS software and called it a day. It's been humming happily along for 24/7 since the chip came out.