As this is the only point I am interested in ... the whole store of value concept worries me a bit. I am perplexed by the concept of using cryptocurrencies as a store of value. Of course this depends on how long you are planning to hold them (but short term gain I would rather call as investment and speculation rather than short term value), but store of value bit is hard since it needs to be linked to something that offers security against devaluation from an increased production or supply. I have a very hard time seeing this in open source software, but feel free to convince me otherwise.
Also, why would it be a pipe-dream to have a wide spread diffusion of a cryptocurrency used in everyday trade? Their intrinsic benefits are way more supportive of this usage than long term hold of value. I believe we have only just begun to see the diffusion of these coins and that there is much that can be done to support their diffusion.
"What is money?" and "how does it work?" are two more deep questions and I'm hardly the guru re: either of them.
I think that "ordinary users" who only want these coins so they can buy things are having a very difficult time understanding this system and keeping it at least as secure as their ordinary bank and credit cards. I think this provides a serious limit to the utility of cryptocoins for that purpose.
I think that the value of any money comes from the fact that other people want it. Why do other people want BTC, USD, AU, Pb, booze, women, or whatever? Who knows. That's a matter of crowd psychology that I can't answer. But we can observe that this happens. If everybody decided they no longer wanted any of those things, and they all ran for the door at once, then the value of those things would plummet.
Very few people can properly and deftly deal with multi-currency accounting. (Which is one of the issues my effort is dealing with.) This includes most merchants and merchant software. Although a handful of places accept BTC (% wise) how many take any other 2nd tier coin? (I'm lookin' at you LTC, PPC) Very few. I just don't see how the blizzard of other coins is going to work it's way into that ecosystem.
However, if you're holding these coins as an investment, however speculative that may be at this time, it's likely that you'll deal with much larger quantities, and it would therefore make more sense to expend the effort to deal with multi-currency accounting. That's why, IMHO, the best use of these coins will ultimately prove to be as a store of value. If so, then there's a very large market that can accommodate many, many coins.