I don't understand how people claims that it will take thousands of year to crack the private key of a wallet. While yes with today computers or even clusters, it will take a thousands of years, I'm pretty sure that in a 20 years from now it will be a matter of days if not hours.

If we look at our computing power in the 60 and compare to the 80s, the whole computing power in a Saturn V rocket and the lunar module could fit in less than an Apple computer of the time, and if we compare the computing power of the 80s (Cray for example) with late 90s and easly 2000s, the power of supercomputer of the time could be assimilated to the power of a single chip, and between late 90s and nowadays is even more.... well lets put it this way, the faster supercomputer of 2000 in terms FLOPS was IBM ASCI White with it stagering 7.226 TFLOPS !! Well that's less than last year 7990 a Dual slot graphic card that you can set on your personnal desktop.

This without taking into consideration, alghorithms breakthrough or technological ones such as Quantum computing, hybrid system or even on the basic level, moving from Silicon to graphen would have a huge impact!