The CIO's concern regarding "viability" and "scaling" is rooted in the risks associated with tightly coupled, point-to-point integrations. Using @future methods for direct callouts creates a "spaghetti" architecture where Salesforce must manage the specific endpoints, authentication, and error logic for every external system.

The architect should recommend implementing an Enterprise Service Bus (ESB). An ESB acts as a centralized middleware layer that provides mediation, routing, and orchestration. By moving the integration logic to an ESB, Salesforce only needs to send a single message to the bus. The ESB then takes responsibility for delivering that data to multiple business units and external systems. This decouples Salesforce from the downstream systems; if a target system changes its API or is replaced, only the ESB configuration needs to be updated, not the Salesforce Apex code.

While External Services (Option A) provide a low-code way to call APIs, they still represent point-to-point connections and do not solve the broader orchestration and scaling challenges. ETL tools (Option C) are designed for bulk data movement and would not satisfy the need for the near real-time updates that the existing callout logic likely supports. An ESB provides the "quality of service" features—such as guaranteed delivery, retries, and protocol transformation—that are necessary for a growing enterprise to maintain a stable and scalable integration landscape.