Cardano uses the Hierarchical Deterministic key generation scheme (specifically that of BIP44-ed25519), which is an offline process that can be done without an internet connection. As such, there is no way to know that your master key has been compromised unless it is used to submit a transaction. However, clever use of NFTs and Plutus scripts enable us to construct a variety of risk-management protocols with associated trade-offs. Even simple constructions as outlined here may be used create highly complex output gaurds.
A super simple example is that of a "death protection" scheme that I use with my family. My primary key is under my secure control, but in the event that key becomes inaccessible, there is a second, highly accessible key that is only unlocked 10 years from now. Here's the JSON formula I use to build the script-address:
{
"type": "any",
"scripts":
[
{
"type": "sig",
"keyHash": "<PRIMARY KEYHASH>"
},
{
"type": "all",
"scripts":
[
{
"type": "after",
"slot": <FUTURE SLOT NUMBER>
},
{
"type": "sig",
"keyHash": "<EMERGENCY KEYHASH>"
}
]
}
]
}
However, no matter the complexity/design of your scheme, a permissionless blockchain without trusted third-parties will NEVER protect you against catastrophic loss of a master secret.
The only real way around this is to admit some form of centralization/third-party authentication. The question then becomes, in what form should such insurances be?
IOHK actually wrote this paper about "proofs-of-ownership" and "secure hidden fallback" mechanisms that may be leveraged for such purposes.
Quick Summary:
A back-up key can be created upstream of the initial key derivation; one that is never used, even for signing transactions. The only time one would use it is to prove ownership of a child signing key. Ideally, such keys would never see the light of a network and would be kept separate from the primary signing keys. These back-up keys can be used to prove ownership of their associated wallets. This can be extremely useful in the event a (side)chain is rolled back due to some massive security flaw, among other scenarios.