When an Orkney naval base would be worthwhile

Would Orkney still be a good place to base Royal Navy ships?

Potentially, but only if enough ships and operational demand exist to justify rebuilding and sustaining the base infrastructure.

The location remains potentially useful, but only if the fleet is large enough to justify the infrastructure. A base is not valuable in isolation; the number and missions of the ships it supports must repay the cost of facilities and personnel. The answer provides a concise force-structure test for proposals to revive historic naval stations.