So, you'll be replaced with lighter, more flexible, more competitive entities that do "editing, promoting, designing, and selling" and focus on competitive digital distribution.
The OP suggests that publishing model is obsolete and good riddance with publishers. So what he is suggesting is to get rid of publishers who take manuscripts, process them, and deliver them to market. You then suggest they be replaced with entities that do the same thing. The entities you describe already exist and they have a name: publishers. Will they have to adapt to the market? Yes,and those that hope to survive must. Would the market be better off if there were no publishers willing to risk author advances, process manuscripts, and deliver them to the market? I believe so, yes.
It is easier to change the specification to fit the program than vice versa.