I don't have any specific soft-forks in mind. On chain privacy is a really tough problem to solve. For one thing there's a fundamental cryptographic trade-off where you either risk inflation or retractive total loss of privacy (perfect binding vs. perfect hiding, pick one). At a more mundane level any advanced (compared to what we have now) cryptography makes auditing the supply more difficult, tends to need more block space, breaks pruning and might break lightning.

Cryptography Stack Exchange

Difference between computationally and perfectly hiding (binding) properties

I am new to Cryptography and has a trouble of understanding the difference between perfect and computationally hiding (binding) properties of a com...