... I know the Myspace analogy technically isn't that great of one. I'm speaking more in terms of Bitcoin being over-hyped and there potentially being a better successor to come along.
You have to understand the context of "better successor". Bitcoin was not an incremental improvement on prior attempts at digital cash. It was a large breakthrough in computer science (specifically solving global consensus; the "byzantine generals problem"). The problem stood unsolved for decades. The network-effect surrounding the solution to this problem as applied to digital money, as you can see with bitcoin's success, is huge.
Possible incremental improvements over the current implementation details of bitcoin are nowhere near interesting enough to unseat bitcoin's dominance. It's not proper to compare bitcoin to specific companies (FB, Myspace); a far better analogy is core internet protocols.
Bitcoin is the first viable protocol for trustless exchange of value. It's more analogous to things like SMTP or IP. Did improvements to those protocols exist? Of course... But when we're talking about things that are a large break from the past, "good enough" plus first usually wins over incompatible alternative approaches.
It's also worth noting that these protocols evolve and incorporate new ideas. Bitcoin has the same properties; if new ideas come along that are indeed very beneficial, it's likely they'll be incorporated into bitcoin.
For me to get worried about successors, I'd have to see fundamental new solutions to the problem of achieving trustless global consensus over an insecure network. No alt does that. And even if one did come along, I'm not sure quite how it would do it massively better. The fact is, bitcoin's consensus solution works, and that's all it takes to launch the virus of digital money.
For the non-technical person, think of it this way: The Bitcoin protocol is analogous to the English system of measurement. Do we have a better system of measurement? Of course. The metric system is better because it is based on a factor of 10. However, the English system is still predominantly used in many countries because it would require an enormous amount of effort for society to change to the metric system. We would have to change mile marker signs on roads, change the the tools that we use to measure length and quantities, change the game of baseball, basketball, football. These changes would not be worth undertaking when the English system is "good enough."
Protocols are similar to systems of measurement. IPv6 is better than IPv4 but we still use IPv4 because in order to change solely to IPv6 we would have to change existing routers, switches, servers, NICs, OS, ect. IPv6 has been in existence for 15 years but has yet to be used as the primary Internet Protocol.
Bitcoin is a wealth transfer protocol. For society to switch to another protocol as the primary currency and payments system, mining operations would have to be changed, exchanges and wallet services would have to switch to the new protocol, hardware wallets such as the trezor would have to be redone, ect. While bitcoin is still young, the possibility exists that a better currency could take its place, but I believe we are near the point of no return and society will choose not to change existing infrastructure because a coin is slightly better. Myspace and Facebook are just applications on the internet that users can switch back and forth between willy nilly without any repercussions or changes in infrastructure.
And this:
The "Myspace" / "Facebook" analogy breaks down because of the economic concept of opportunity cost.
There is essentially nothing preventing a person from reaping as much utility as they're going to get out of both Myspace and Facebook simultaneously. Having a Myspace account in no way inhibited you from just going and signing up for Facebook when it became available. In fact it's probably the opposite, the kind of person that even cared about Myspace would also like Facebook.
With Bitcoin versus some unspecified future altcoin, there is a serious barrier. You don't have infinite money.
In addition to this, network effects are stronger for currencies than social networks.
Content on a social network depreciates rapidly. Currency does not (absent limitless issuance of more units).
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