Cunningham is a great litmus test for Fury and one I think he'll pass. Cunningham is the most athletic guy with out a doubt but he's not going to be able to get Fury's respect and he'll also struggle to get beyond the Fury jab (which despite his size is very fast).
For the guy saying that Cunningham will lose just because of his size, I think you're over simplifying things a tiny bit and have also forgotten the vast age difference as well as the "ring age" difference. Fury has only really had 1 genuinely tough bout (don't mention him being dropped by Neven Pajik, it was the first McDermott fight) whilst Cunningham has made a career from having hard fights. Those wars with the likes of Hernandez, Adamek (the first fight anyway), Huck and Ross at world level will take a lot of miles and add them to your clock.
At 36 and with the physical disadvantages and the wear and tear I'll certainly be backing Fury.