Not that it's being considered, but what an interesting experiment it would be should the RAF ever introduce a Boom into service.
The future of the truly multi-role tanker might be a 3-crew member flight deck. With 2 people facing forwards (Pilots) and 1 backwards (Mission Systems Operator).
On operational flights, outside of actual AAR, one person flies the jet (PF), responsible for navigation and all the stuff the PF does now, including maintaining formation position with other tankers when relevant. 2nd person (PNF), in the other pilot seat, is responsible for some communications, including radios, CPDLC, ACARS, Datalink systems, SatComm, etc, monitors aircraft systems and backs-up the PF and MSO, including any mission systems in use. While the 3rd person, the MSO, shares the communications workload with the PNF, but focusses more on the mission systems, timings, fuel plans etc and plans ahead, maintaining crew SA on the mission as a whole. The lead-tanker MSO might also be responsible for some traditionally C2 work, such as allocating receivers to tankers based on requirements, location, tanker saturation and fuel available.
When an AAR event occurs the MSO would operate the AAR systems (Boom or Pods) and control receiver aircraft in formation. The PNF would take over control of mission systems, timings, fuel plans etc. The PF still controls the Tanker, navigates, communicates with other receivers joining, maintains formation position with other tankers etc.
The key ingredient to this operating model is synergy, which is facilitated by CRM, training and SOPs developed to include the crew operating as a team. Each person would need to have a good understanding of each of the other positions' roles and know what other members are doing at all times.
When the Multi-role aircraft is being used for other tasks, the flight deck composition might depend on the complexity of that task. For 'simple' AT (is it, ever?) the MSO might not be required. But, if the aircraft is being operated with minimum support, as military operations often are; without the type of infrastructure enjoyed by a commercial airline, flying familiar routes on a regular basis. The MSO might take on some of the roles of load control, movements staff, the Loadmaster, Purser, Flight Despatch, Planning Staff, Performance Engineer etc. The Captain would still do the traditional captain work and the PNF would integrate somewhere between the 2. With a suitably trained and qualified MSO they could provide a lot of support to the AT role and increase efficiency while reducing some costs associated with handling support. (Noting that Crew Duty may be affected should the MSO be required to accomplish a lot of work on the ground.)
Current and future operators might take a mission-oriented approach to operating policies and procedures and carefully avoid a 'how we used to do it' approach, or a 'I've only ever operated tanker X so therefore Procedure X is the only way to do things.'
Capturing this 'synergetic' tanker-crew operating policy in writing might be a challenge. Detailing a fluid, 3-dimensional, multi-layered operating concept in a 2-dimensional set of orders and instructions could require some effort. Training it might take months. Convincing old-heads might be almost impossible.
I'll get me coat.