There has been several national currencies that has gone from a viable currency to a legal tender that has resorted into a shitcoin equivalent. Does that make the currency to cease?

No.

What such nations needs to do is to assemble a strong economic team to work around, improving the value of such currencies.

Cryptocurrency is not very different in this regard.
Not withstanding how long this bearish run takes, if we don't put in the right measure to address the pending issues, not much will change.

One positives i want us all to take home is that; cryptocurrency has really come to stay. It's only a matter of time and getting the parameters right; then there will be light at the end of the tunnel.