I think we'll be surprised what a fresh face and fresh ideas will do for the current crop. That's not to diminish Klopp at all, but he's been honest that he's run out of energy - and our tactical approach has become quite stale. Slot isn't anywhere near Klopp, but I think just bringing a new way of playing in will benefit loads of players who currently look a bit fazed.
Then you add a smattering of new players there, maybe blood a couple of youngsters who we didn't expect much from (ala Quansah and Bradley this year) and we'll be fine.
I'd probably be signing four or five, but we'll see if we do that many. I'd probably want a CB, LB, another midfielder and at least one attacker. Apparently Slot loves wingers so I could see us adding a couple there. At least one or two surprise departures as well I reckon.