Bitfinex makes less money from fees if BTC is only worth $100. They sell several other contracts (LTC, TH1, Darkcoin), but I think they are all heavily correlated to the price of BTC.
Correct if you assume that the trading volume in dollar would fall as well. If the dollar volume was to remain constant it would not actually matter since the amount of traded btc would simply increase. My question was a bit deeper though. Is the well-being of Bitfinex directly correlated to the price of btc? Does bitfinex hold significant company funds in bitcoin etc. or is it independent from the trading value of bitcoin?