Bitcoin can be perfectly successful as a "niche currency".
Sorry, with all the due respect, I don't get what you mean. Which kind of "niche usage"? Of course,
technically Bitcoin
can work perfectly as a niche currency. But I just don't see which kind of niche that could be. Some altcoins are aiming to fill some niche, however Bitcoin was never meant to be a niche solution. It could either become global currency, or global value storage, or global anything - the key word is
global here. Why and how Bitcoin could limit itself to a niche? Any scenario (please consider real world scenarios based on the current state of it)?
In an alternative scenario, speculators could sell almost anything, anarchists would again become the dominant user group, the price would be much lower, and that would be fine too.
I suppose real anarchists would rather move to Anon-type coins like Dash, Monero or Zcash. I would not count on them alone. Fortunately, speculators and anarchists are not the only users of Bitcoin.
And the current "everybody wants to have it" frenzy is only due to Bitcoin's growth. If the price evolution becomes flatter (e.g. like a fiat currency) because of higher adoption and less volatility, there would be less incentive to buy Bitcoin to make profit.
Right, the frenzy is due to the growth. But if price evolution becomes flatter, there still be a speculative reason to hold Bitcoin. The same as with gold - the gold price currently is high due to speculators buying and keeping it - the real value of gold as a metal is much lower. However 'everybody wants to have it", because it is considered to be rare and more secure than USD. The same could be with BTC if the price evolution becomes flatter.
Bitcoin's price would be much lower if there was no speculation on future usage. I consider speculation on future usage a completely legitimate strategy, because Bitcoin has an enormous potential. But it's false that it wouldn't work as a niche currency at $100 a coin.
Yes, basically speculation is the key element in the value on almost any asset, including the ones like gold/silver etc. As to the part I highlighted in bold - please explain, honestly, I still do not see any niche usage scenario for Bitcoin - only global ones are viable in my view.