OK, thanks. Deleting old blocks is a tricky prospect. I will be looking forward to seeing that algorithm…
Data chains are an interesting turn of events.
Vitalik Buterin came close to predicting this a year ago: Vitalik Buterin on MaidSafe's consensus mechanism
One could make an even more tortured argument that I predicted it 3 years ago 
https://groups.google.com/d/msg/maidsafe-development/hz30YduO4I0/1pEER7p2shAJ
It seems like Maidsafe and Ethereum are closing in on a similar solution, Maidsafe data chains and Ethereum shards. They are just approaching it from the opposite direction.
Maidsafe started with a highly scalable solution, and is adding blockchain inspired techniques for security and consistency.
On the other hand, Ethereum started with a highly consistent and secure system, and is adding sharding techniques (inspired by Maidsafe?) to make it scalable.
I am a much bigger fan of the Maidsafe approach for a number of reasons. However, Ethereum has the funding and marketing edge.
The race is on. Exciting times ahead.