The fact that these algorithms are obsolete does not change their importance, but it is the ability to find the private key that will make them useless, and if a serious vulnerability is found, the private key can be accessed, as happened with The EFF's US$250,000 DES cracking machine
The vulnerability of DES was practically demonstrated in the late 1990s.[32] In 1997, RSA Security sponsored a series of contests, offering a $10,000 prize to the first team that broke a message encrypted with DES for the contest. That contest was won by the DESCHALL Project, led by Rocke Verser, Matt Curtin, and Justin Dolske, using idle cycles of thousands of computers across the Internet. The feasibility of cracking DES quickly was demonstrated in 1998 when a custom DES-cracker was built by the Electronic Frontier Foundation (EFF), a cyberspace civil rights group, at the cost of approximately US$250,000 (see EFF DES cracker).
Quite simply, if this happens, Hardfork will be needed, but I think then that Bitcoin is the last problem as DNSSEC, SSL, IPsec, TLS, SSH and many other systems that we use daily that use SHA-256 Algorithm.