The problem isn't simulating the look or design, but the kinetics. Classic-era toons (Freleng, Clampett, Avery, et al.) derive from a world that is purely graphical. Mo-cap derives from the purely physical. Toons live in graphical dimensions that vary according to the toon. Mo-cap lives in the Newtonian universe.
Much can be achieved by mo-cap to simulate other physics. But bottom line, Daffy Duck is drawn, not moved. His movement is a result of drawing. Mo-cap movement results in drawing.
It'll be interesting to see what Zemeckis does.