As networks improve and new services emerge, questions arise that affect service deployments and network choices. The Internet is arguably a successful example of a network shared by many services. However, combining heterogeneous services on the same network need not always be the right answer, and technologies such as virtualization make deploying new services on separate networks increasingly more viable. So, which is the right option? The question is not unique to networks, and there is a large body of work in the manufacturing systems literature that explores the trade-off between flexible and dedicated plants. This paper highlights an important feature missing from these earlier works, namely, the ability to ``reprovision'' resources in response to changes in demand. It demonstrates that this feature alone can affect the choice of network solutions, and argues for models that incorporate it.