Blockchain is the technology behind Bitcoin. The advantage of blockchain is that every time you do a transaction, a copy of all transactions ever done will be downloaded to your computer. This will make it impossible to cheat the system. But eventually it will create a capacity problem. I have not updated my knowledge of the blockchain technology for some years, they might have made a fix for it.
I can see that this is an opportunity for Kodak to do business, hence the stock market hike. For us as users the pricing of this service will be interesting to see. If you don't sell any pictures it could be a costly insurance.