Certainly countries that take a draconian measure to shut down the internet will have the same effect on blockchain. If one cannot access it, whether the info is on a central server or blockchain there is no getting to it.
That said, many people, like the Chinese ,found ways around it and that will most likely happen as technology advances.
As for the size of the data, that is an issue. One thing to keep in mind, the only thing on blockchain, so far, is text. That is a lot smaller than videos and pics. Those are uploaded to cloud services although we are seeing the potential of video being hosted in a decentralized manner.
Fortunately, the memory and speed capabilities keep increasing exponentially.
That all fits in with what I've been thinking so far. So what that means, I think, is that blockchain is a special-use case of the internet. There are certain uses that it will be very valuable and better than what came before - which is great!
However, that also suggests to me that it won't necessarily be as revolutionary or disruptive as the internet. Since it's only a special-use aspect of the internet, it's hard to imagine that the part will be greater than the whole. Then again, just because it's hard to imagine, it doesn't mean it's not true.
(And, of course, Amazon is only part of the internet, and it's worth a fuck-ton of money.)
Ten years from now, most of the world's commerce will be done on blockchain so it is more than just a niche or special case us.
These blockchains are going to effectively be nations down the road. Most of what you do, work, communicate, shop, play video games, watch movies, etc...will all be done on this blockchain.
That is how powerful it can become.
True, the fact that it can/will be so important to commerce pretty much guarantees its significance.
It will revolutionize science also. We will start following people that actually contributes to advancing humanity and not profits! Can you imagine where we would have been if scientists like Royal Raymond Rife, Nikola Tesla and many more had access to this information!