Blockchains were initially developed to address currency, one of the few applications where true anonymity generally is desired. However, most every other blockchain application will want to evaluate the correctness of the device and its user. This will require forensic auditability, not only of the transaction, but also to validate the identity, capability, and current health of the device instructing the blockchain. Known device, known user, known condition.
The smartphone is anticipated to be the largest holder of private keys in the new blockchain economy. As carriers develop and deploy enhanced connectivity services, including the support for other connected devices such as autos and our homes, and the digital user eases into these new and more reliable services, the most widely connected consumer device will continue to be the application point of interactions.
Smartphones hold keys. Smartphones must be protected.