Two questions to answer:

• If we don't have a catalog cache (CollectionCatalog), but always read/write from/to the durable mdb_catalog, can we have a significant reduction in complexity?
• Can we get OK performance by always going to the durable catalog?

If we don't have confidence in the first, we should not consider. If we know we cannot achieve the second, we should don't consider either.

This ticket should probably focus on answering the first question.