If Bitcoin becomes widespread enough that most people hold their savings in it, then it will greatly and permanently reduce liquidity in the financial system, lead to a decrease in consumer spending and cause major ructions in the global economy.
Everyone will try to come up with his own theory when it comes to the impact of bitcoin on the economy, but i won't say much concerning this because bitcoin will always remain, in serving it purpose of creation since it's on a decentralized digital network, another thing to put in consideration is the bitcoin network, which also experiences liquidation whenever the market falls below expectation, this is not because of the nature of bitcoin, but the way people engage on making their investments or trades in it.