That's certainly true, mate. Wide-spread support within the mainstream world will keep cryptocurrencies alive for a long time. It's all a matter of utility, whenever crypto proves to be useful for everyday people. So far, cryptocurrencies like Bitcoin and Ethereum are better than traditional payment systems (despite their current limitations). The fear that crypto will go to zero is largely attributed towards the volatile nature of digital assets. However, it seems very unlikely this happen in the future as crypto is becoming more adopted by businesses, corporations, and even governments worldwide. We even have centralized cryptocurrencies like XRP and Libra (soon) which will further increase the adoption of crypto and Blockchain technology.
If all governments reach a common agreement to stop people using crypto, then it will go to zero without a doubt. However, knowing that governments have certain disagreements among them, this seems like a very unlikely scenario in the future. Which is why, it's safe to say that crypto will survive for a very long time. Whatever the price will be in terms of Fiat, no one knows for sure. In the end what really matters is crypto's usability instead of pricing, in my own opinion