It does have severe ramifications for other crypto currencies. The other crypto currencies are modeled on Bitcoin, with just some parameters different. If Bitcoin can be compromised, this nearly immediately means the other currencies can be compromised as well. The end of Bitcoin would thus also signify the end of most, if not all, other crypto currencies.
Not all cryptocurrencies use proof of work like bitcoin, some of them use proof of stake, combination of proof of work and proof of stake or maybe some completely different mechanism.
Yes, other currencies which use proof-of-stake are also vulnerable to 51% attack but this is nothing new, this is a fact known from the beginning, it is explained in the original whitepaper by Satoshi Nakamoto.