Pretty sure someone has corrected you on this point already, there is no single central world bank that regulates currency, as such all major governments would have to be on board to destroy the use of cryptos, in any case your proposition is baseless, there is no way for you to know governments are going to ban bitcoins.
"Give me control of a nation's money and I care not who makes the laws." Mayer Amschel Rothschild
"The Liberty Dollar (ALD) was a private currency produced in the United States. The currency was issued in minted metal rounds (i.e. coins), gold and silver certificates and electronic currency (eLD). ALD certificates are "warehouse receipts" for real gold and silver owned by the bearer. According to court documents there were about 250,000 holders of Liberty Dollar certificates.[1] The metal was warehoused at Sunshine Minting in Coeur d'Alene, Idaho, prior to a November 2007 raid by the Federal Bureau of Investigation (FBI) and the Secret Service.[2] Until July 2009, the Liberty Dollar was distributed by Liberty Services (formerly known as "National Organization for the Repeal of the Federal Reserve and the Internal Revenue Code" (NORFED), based in Evansville, Indiana. It was created by Bernard von NotHaus, the co-founder of the Royal Hawaiian Mint Company.[3]
In May 2009, von NotHaus and others were charged with federal crimes in connection with the Liberty Dollar and, on July 31, 2009, von NotHaus announced that he had closed the Liberty Dollar operation, pending resolution of the criminal charges.[4] On March 18, 2011, von NotHaus was pronounced guilty of "making, possessing, and selling his own currency".
"Attorney for the Western District of North Carolina, Anne M. Tompkins, described the Liberty Dollar as
"a unique form of domestic terrorism" that is trying "to undermine the legitimate currency of this country".[28]
http://en.wikipedia.org/wiki/Liberty_DollarThe devil is in the details, bro:
A federal grand jury brought an indictment against von NotHaus and three others ...charged with one count of
conspiracy to possess and sell coins in resemblance and similitude of coins of a denomination higher than five cents, and silver coins in resemblance of genuine coins of the United States in denominations of five dollars and greater, in violation of 18 U.S.C. § 485, 18 U.S.C. § 486, and 18 U.S.C. § 371;
one count of mail fraud in violation of 18 U.S.C. § 1341 and 18 U.S.C. § 2;
one count of selling, and possessing with intent to defraud, coins of resemblance and similitude of United States coins in denominations of five cents and higher, in violation of 18 U.S.C. § 485 and 18 U.S.C. § 2; and
one count of uttering, passing, and attempting to utter and pass, silver coins in resemblance of genuine U.S. coins in denominations of five dollars or greater, in violation of 18 U.S.C. § 486 and 18 U.S.C. § 2.[24]
Bitcoins aren't actually coins (smh)