Wrong.
Basically its these two limitations (below), both of which will depend on the engineering design of the chip but are in general a characteristic limitation of silicon. the first limitation, "settle speed" will depend greatly on the second limitation, heat, so if you cool the core to sub zero temperature you will hit the limitation #1 barrier at a much higher clock speed. Hence why overclocking depends greatly on cooling.
from wiki:
1# After each clock pulse, the signal lines inside the CPU need time to settle to their new state. If the next clock pulse comes in too soon, while the signals are still settling (before every signal line has finished transitioning from 0 to 1, or from 1 to 0), the results will be incorrect. Chip manufacturers publish a "maximum clock rate" specification, and they test chips before selling them to make sure they meet that specification, even when executing the most complicated instructions with the data patterns that take the longest to settle (testing at the temperature and voltage that runs the lowest performance).
2# Some energy is wasted as heat (mostly inside the driving transistors) whenever a signal line makes a transition from the 0 to the 1 state or vice versa. When executing complicated instructions that cause lots of transitions, higher clock rates produce more heat. If electricity is converted to heat faster than a particular computer cooling system can get rid of it, then the transistors may get hot enough to be destroyed.
I look forward to seeing some impressive new tech in my lifetime. However we're probably stuck with silicon for a while yet.