I think the killer application for homomorphic encryption (HE) will be on the regulated and sensitive data as you have mentioned. In healthcare, high accuracy machine learning requires massive datasets and it is difficult to get your hands on the data mainly due to privacy concerns. If HE can make data available to be analyzed without compromising the patients' anonymity it will be a game changer and perhaps can relax on the accessibility of the sensitive clinical data in the near future.
Just wondering, can we not achieve similar privacy using secret sharing (SS) cryptography for anonymity? With (SS) unlike HE, you can perform arbitrary calculations in the encrypted domain [2].
[1]How to Share a Secret:
https://news.ycombinator.com/item?id=31817716
[2]Secure multi-party computation:
https://en.m.wikipedia.org/wiki/Secure_multi-party_computati...