1) A common "universal" transaction data source
2) A shared, readable format
So the thought occurred to me that as soon as blockchain apps/currencies became popular, people would want analytics on them. There would thus be a startup opportunity for unprecedented analytics visibility into transactional data from a third party without needing to build bespoke integrations into high security/compliance systems.
If a blockchain backed currency was widely used, a third party could easily estimate the real-time sales flow of every brick and mortar store location. You could have real-time auditing and quarterly tracking of both public and private corporations available from a third party. Asset transfers, smart contracts, and their real world equivalents could be instantly monitored - allowing the early detection of emergent supply chain bottlenecks.
The problem with all of this is that in the 5 years since I had this idea, the only use cases for BTC and other cryptos has been price speculation. The market for such analytics products is effectively zero.