Because of the sheer performance challenges, and the availability of SGX as an alternative, and also the competitiveness of MPC, I think most use cases struggle to justify selecting homomorphic encryption as the best choice.
To me, who is involved in related fields but not FHE directly, it seems like practical FHE is probably 15 or more years away, even for niche use cases.
Intel SGX - allows you to run your code on a someone’s hardware fully assured that owner can’t get nor your code not your data.
MPC - Multi-Party Computations. To protect your data and algorithms, you split data and code between multiple parties in special way that prevents them from knowing what exactly was computed.
To me, who is involved in related fields but not FHE directly, it seems like practical FHE is probably 15 or more years away, even for niche use cases.