What you said is true, its something we would have to figure out on the way.

What I have in mind is -

1. Topic specialized models which are frequently updated maybe every month or two.

2. Fact Checking & Moderation specialized, models which moderate or do fact checking on other model's output.

Kind of a chicken and egg problem. But I believe on the way we will be able to minimize the effects of hallucinations through output validation (both neural and rule based).