Well what we really need to continue to improve clock cycles is better cooling. Overclocking modern chips is really easy and all you really need to get a pretty solid increase in speed is a decent cpu cooler. Yes to get drastic increases you need to up voltage to the chip and there are concerns about the chip degrading faster at higher clock cycles, but for the most part a solid increase in speed can be achieved simply by telling it to go faster and making sure it doesn't overheat.