It reminds me of similar discussions we had within DFINITY, and yes, this unaesthetic namespace prefix in the method name was the least bad solution we found.
Maybe something prettier than a full domain could be used? Create a simple canister where you can register prefixes? Or leave it free-form and hope that clashes won’t happen? (But that seems not good enough)
One alternative in principle is to have proxying helper canisters if one has to provide incompatible interfaces, or possible (extending the system) a scheme where a canister is reachable under multiple IDs (like vhosts). But unfortunately such helper canisters don’t always work transparently (e.g. queries, although that lack of compositionality is in a way a telltale sign that our application model isn’t that great yet), and I am not sure the complexity of adding “virtual canister ids” will be worth it.
If only we had a capability-based model 