I agree that the basic idea is pretty interesting but I`m not actually clear on what you are trying to say here. Are you asking whether the BTC network`s hashpower will every be utilized for the things these supercomputers are currently doing? Wondering whether network hashrate will ever stop growing? Whether BTC as a network / phenomenon is ever going to fail?
I`m not an expert, but it is my guess that even if the raw hashpower of the network is greater than X number of supercomputers, the supercomputers do have the ability to accomplish more complicated tasks or more specific tasks. The comparison of GPUs to CPUs comes to mind - where a GPU is a crowd of dumb people who can do repetitive tasks and a CPU is a single genius who can do extremely complicated tasks quickly. My understanding is that a supercomputer has much better executive functioning, and so although the BTC network`s massive crowds of `dumb people` can hash faster, it may not be accurate to characterize the network as being more powerful in absolute terms.
I`m open to being corrected on this if somebody with a better background in computer science or networking can explain better or more technically.
