Full control is a pipedream, and really isn't something you see at any big club.
But letting him identify 3-4 experienced players this summer whilst letting the SD's supplement with their conveyorbelt of teenagers is something that could feasibly happen.
Then if (big if) things go well, the cycle becomes manager asking for a couple specific players every few windows with SD's handling the players that are signed with a view towards developing them (either in house or on loan). That would get us somewhere closer to the model we saw under Abramovic and would allow the manager to feel he is able to plug gaps / pounce on players he wants, without him being responsible for the upkeep of the entire squad + loan army.