I think bitcoin is a currency, but can be traded like commodities in the market exchanges.
Just like USD, a fiat currency, but peoples can use it for trading in forex market too.
For now, bitcoin market volume is not a good as stock market volume. Once bitcoin become global currency, it will have more volume i believe.
Yes it can be and all we know that bitcoin is made to be a currency but with the current state of how people use bitcoin, it might can't happen. Since the price is growing drastically, we perceive bitcoin as an asset and we less to spend it since we're hoping that sooner the price will grow more.
Perhaps I don't think it's a commodity when it comes in economic terms. Otherwise it's greater than asset than to be a currency, and that's the deal.