For now, I think it will hold it's reserve status just because of how the exchanges are setup. Recently, I learned, if I want to buy coins on coinbase, consider buying ETH or LTC instead of BTC. I think BTC may even gradually lose gateway status of the USD to Crypto coin. I know if coinbase supported Dash, I would just be using that with the near instant transactions.

That said, once a big pool of BTC is on an exchange, we can trade it back and forth on the exchange without paying network fees. So it functions as the reserve currency on the exchange. And the price on the exchanges can be managed by people who do arbitrage, buying huge volumes of BTC and paying small percentage of network fee. Also, if the exchanges get lightning network going, BTC stands a good chance of remaining the reserve currency for a number of years.