Bram Cohen, author of the BitTorrent protocol, spoke about data structures for scaling Bitcoin.

Link to slides: https://drive.google.com/file/d/0BwQpYqkQqA9cc0N4SlN2M05MS1RRRy1vZV9tZEE2VC1ZdUh3/view?usp=sharing

Blockchain growth results in challenges for scaling nodes: Downloading the complete blockchain, running a lightweight node, and validating transactions in memory all become problematically expensive. Two approaches to lessening load will be presented: A transaction bitfield so transaction validation can be done with no disk access, and a very optimized general purpose Merkle trie to allow nodes to be pruned and allow the myriad other use cases of Merkle tries.