Recent musings in the Israeli press concerning the offices of the two Chief Rabbis has given those of us outside of Israel much to ponder.
When changes were made in some of the organizations in which I worked a careful analysis would have been done looking into why something had been set up initially and what benefits and/or disadvantages would result from any contemplated change.
I am not sure though how one would do a Halachic or theological benefit analysis.
Though a purely domestic issue, there are perhaps some points from the Canadian experience which might be of use in such discussions.
Canada, with French and English forming two founding cultural groups and a policy of bilingualism in a number of areas has adopted systems which see individuals selected from each of the two blocks in an alternating fashion.
The Office of our Governor General comes to mind. Given the multicultural nature of our society we also may focus on selections which address visible minorities, ethnic groupings to say nothing of feminism and White Anglo Saxon Protestants (WASPS). These latter two groupings will not be of a concern in the selection of Chief Rabbi candidates though !
Perhaps selecting one Chief Rabbi from either of the Sephardic or Ashkenazi communities and having an identified successor being groomed from the other would aid in smooth transitions and a continuum of experience which would draw on their differing backgrounds.