I don't think alternative currencies have a long-term future. The only reason they exist now is because people and governments in most countries are quite ignorant about technology. Once they become more widely used, they will start causing a whole lot of problems* and will be banned by governments.

The real solutions, in my opinion, have to use real currencies or they will face a severe risk of death by regulation.

* Use for illegal activities.

* Problems with controlling capital flow across national borders.

* Problems with estimating money supply in an economic system etc.