I'm 'in' for Rangnick to come in as both interim manager and DoF to re-set the club initially,
and to then continue as DoF with a manager of his choosing.
If he only wants a short term appointment he can pick his replacements in both roles.
As part of that I'm not sure too many high profile managers will want to come in to effectively play 2nd fiddle to a DoF charged with rebuilding the club, as many would want to do so as manager themselves.
Regardless of the decision/s IMO the most important decision is they work together and balance each other. IF an inexperienced manager then an experienced DoF & visa versa.
As for Van der Sar and Overmars IMO they are both making themselves 'available' for the jobs at Barca with the upcoming elections.
Other managerial options for the list would include the likes of Jardim, Rose, Hassenhuttl.
Advantage with all 3 of Hassenhuttl, Rose and Nagelsmann being all 3 have worked under Rangnick at RBL or RBS.
For mind if we are to replace Arteta this season the same rule of thumb applies regrds to potential replacements as it does for incoming transfers = PL experience is crucial if you want / expect anything beyond 'new manager bounce'.