Can bitcoin take Fiat's place in time? Suppose it does? Can govetment step in and stop this program?
NO government Can not any step for stop this Program. Because Its Depend On Miner Networking If the are stop Mining then its happen. But it not possible. The Government can't take any step for stop it because the don't know any record about bitcoin and the don't know where is setup and where controlling.
Government can not do anything, they can just declare the bitcoins and activities related to bitcoins as illegal. As bitcoin is decentralized currency, government has no authority to control and monitor it.