Maybe the thing that I'm most interested in cryptocurrencies is the governance structure. If it is good, the project can work in the long term.
There are some new blockchains that have a lot better governance systems than Bitcoin, but I'm not sure if there is anything perfect. But I think Bitshares is state of the art, with its reward pool, worker system, and committee for adjusting blockchain parameters.
But of course it's not enough. If the community is toxic, a good governance system doesn't necessarily help it. And vice versa, if the community is good, even a bad governance system can produce good results.