Or interest will wane and most will move onto the next cryptocurrency. What makes you so sure the demand will remain (or increase) if there are alternatives?
Bitcoin is the granddaddy. It has a steady roadmap and the devs has released a new technology roadmap earlier this year. It is mostly an optimisation plan, but importantly to reduce storage and bandwidth usage. It is not that the digital currency is stagnating, improvements allow scalability and better implementation.
Every alt coin, unique or not, will need to pursue advancements, otherwise it will be nothing more than a pump and dump. Bitcoin is doing its best to increase capacity to retain its leading support.
Ethereum, well, how long will it remain impartial and decentralised. This may impact its worth, though they do have large corporate support which also supports DAO. DAO has its own discrepancies, being hacked and so on… Smart contracts are a great idea though and has many appliances in the market.
I don’t get why many so many people are comparing Bitcoin to gold, as a storage medium, a vault one may say. The more it is being developed, the more the opportunity to apply it to the market.