Rafa will work with a DOF and he has given his biggest hint thus far.
Taken from a question posted on his blog:
Some football clubs use director of football.
When you were manager at Liverpool, you fulfilled the jobs that two people do at some clubs (Coach and Director of football)
I know you would prefer a Manager type job like you used to have at Liverpool, but would you take on a role at a club without complete control over transfers and all aspects of the club?
Different clubs will work in different ways with their structure. It is possible to work with any structure.