I do not agree that Bitcoin will be the only coin of any value in the future. Even in the event of implementation of side chains. In fact that tecnical failure that Energycoin has suffered points to a need for a diverse crypto space that can serve specialized markets. Though most people in the Bitcoin space like to think that Bitcoin is now beyond certain modes of technical failure that would be hard to correct, most of those thoughts are dead wrong. Every technological thing can break and in times of a broken Bitcoin, other coins would be useful, even if only temporarily.
I think you'll find a use case for using a separate coin for energy and energy conservation, things that Bitcoin was not explicitly deigned to do.
You misunderstood me: I said BTC is still the only one with *some* practical, real life use today. That's all.
I know as much about the future as the next guy, i.e., I know *nothing*
There's a war against money going on (it has been for some time now) and it looks like coins and bills are going the way of the dodo ... but there's also a war on anything decentralized and non-government controllable, so crypto is in for the same fate, I'm afraid.
I said this more than once in several places: the innovation is the blockchain, not the coins themselves
So, these technologies will probably be the foundation and core of the future "money" ... but it will be very difficult, without a major shift or disruption to current affairs, for *any* current cryptocurrency to be useful in that future.