The way we are engineered does not allow for super-great advancements... but I think theoretically its possible.
A lot of our neuronal pathways are regulated and maintained by electro-chemical gradients... or more so just chemicals and the potentials they create. Quick response nerves are myelinated more and thus have less AP potentials to trigger on their way to target and receptors, thus they have faster response time. Some nerves are slow to respond and require elonged stimulation, thus have more gaps in between the myelin sheaths... but these fibers tend to be more for refined movement or endurance.
But that is just associated with motor/sensory neurons.
I am somewhat skeptical of the idea that insulation of neurons will increase IQ. First off the definition of IQ is somewhat subjective enough already, as to how to measure that would be something that needs to be better outlined even though it has been done for decades.
Also, increasing the strength of connectivity within the frontal lobe may make it easier to attain new knowledge or understand certain things, but learning to train or make use of the existing non-strengthened neurons may just be as useful if not more. Just as some people are born with great athletic genes does not necessarily make them great atheletes, they still need to be trained to be able to use their atheletic gift in the most efficient and non-wasteful way possible. Computers also work the same way, a computer is nothing if it doesn't have a built-in firmware or software installed such an operating system that would allow the different functions of the hardware to be used. Quick real example would be how Windows XP does not recognize or utilize more than 2-4GB of DDR ram due to the 32-bit architecture that is was built on. Installing a 1TB hard drive on your computer and only being able to recognize 500GB of it would also be a software issue. The way in which the stimuli are interpreted and defragmented and organized within ones mind is probably more important than the machine in which it is being processed in. Having a large powerful machine is useless if you have no powerful or worthy information worth processing.
They say that we only use like what, 10% give or take a few % of our brains, and that the rest is used for other things and what not? I read somewhere that brains are like silicon based CPUs, the reason our brain only chooses to use 11% is because that way it leaves room for other things, the other 90% or so as a buffer zone. we only process only so many things at a time that matter to us, just as our eyes only focus on one point at a time even though we can visually observe maybe 95% of things around the focal point which aren't significant (peripheral vision).
If we were using up 90% or even 100% of our brain, we'd have no extra room to be able to process everything, on top of that the energy required and the heat produced would be phenomenal. We would actually be very inefficient, because that would mean we have no extra space to process additional information or receive new stimuli. A great analogy was that the more unused % in your CPU listed on your processes, the faster your computer right (that is given a controlled similar process being calculated). The same should apply to the human brain, the less % of our brain we use to do a normal task or whatever task it is efficiently and as desired, the more efficient and "powerful" our brain would appear to be.