To really replace the seatback screens I think the airlines should do the following:
1) Provide an empty slot at eye level in the back of the seat so I don't have to spend 5 hours looking down
2) Have at least 1 outlet per seat
3) Rent out a few tablets & chargers for those who don't have enough for the whole family or forgot theirs at home
I think the best part about getting rid of these screens is the additional legroom in economy without those entertainment boxes.