These days, I've been seeing everyone talk about the upgrade/maintenance of a certain mainstream public chain, and whether the ecosystem will take the opportunity to migrate something.

But I instead thought about cross-chain issues: if you really move, how do assets and messages go over, and who do you really trust?

To put it simply, a single cross-chain isn't just about "a bridge."
You have to trust that the source chain itself won't rollback/reorganize to erase that transaction;
you have to trust that the target chain can correctly verify the proof from the source chain (whether it's a light client or third-party verification, anyway there's a "why should I trust you" step);
you also have to trust that the relay/forwarder won't act maliciously or at least will be caught if they do;
finally, in the contract implementation, bugs can also break all trust.

What I like about the IBC approach is that it clearly separates "who to trust":
it's more about trusting the chain and verification logic, rather than trusting a group of multi-signature signers' integrity...
Of course, the implementation still needs to be observed over time, don't rush into it.

I'll be a bit slow to react, because rushing in cross-chain stuff might just be a trap.
That's all for now, I need to get to work.