I've got this idea, to try and recreate the Doctor Strange reality bending effect. With that I mean the one where the floor peels back and twirls on itself. I thought it would be relatively easy to do, but I've found myself with some problems, I tried to add loop cuts to a plane to act as steps, use the edge split modifier, then the solidify, and lastly the simple deform. But it affects the whole mesh so I used a vertex weigh proximity modifier, but this one only affects on one point. Is there a way to do this effect without using drivers and making the scene very over-complicated? Image of the actual effect for reference
Actually your idea of using the Simple Deform modifier seems to work with the Twist option and an empty as Origin that you move on the X axis. Once your good, parent both the stairs and the empty to a new empty that you rotate 45° on the Y axis:
In the clip you show, the stairs don't even seem to bend on their height, they just duplicate the first stairs and delayed a bit the animation, imho it's as simple as that, but you can also deform it a bit with a Lattice or a Mesh Deform modifier.