A problem waiting for a solution is a solid road system with easily removable cleats and walkable shoes. I don't understand why walking and road shoes must be mutually exclusive.
Walking comfortably for more than a few hundred feet requires a flexible sole.
Riding a road bike efficiently for long distances requires a non-flexible sole.
Hence the mutual exclusivity.
Even with removable cleats a road shoe is not going to be walkable. Your dilemma was the reason SPD and the other recessed cleat systems were invented. Why are you so bent on a "road system" when what you are telling us you want is Shimano's SPD? You said you wanted:
1. A walkable shoe
2. No float
That's SPD. It's the solution to the problem you mentioned.