I'm afraid we probably still have decades of polygon rendering ahead of us. Voxels require such a huge amount of memory that it's difficult to reach an acceptable resolution. Minecraft with it's cheated voxels illustrates how at the time of it's release the technology had a resolution similar to Atari 2600 blocks.

Even the demos from Euclideon result in some dodgy looking objects and textures in the near field. The resolution isn't there yet.

As you're surely aware square bitmaps and textures for 3D objects need simply the memory to fit the resolution of one side squared.
Voxel objects need the memory to fit the resolution of one side cubed.

I'll sum up why it should take decades for voxels to overcome polygons is because polygon graphics are a moving target. If the state of the art for polygons somehow hit a snag and was frozen in time then voxels might quickly catch up in a number of computer generations taking perhaps five or six years. But that fox called polygon graphics is going to keep running at a faster pace than voxels can keep up. For every doubling of voxel resolution polygon textures can quadruple. It won't be until the increases in resolution for polygonal graphics starts hitting diminishing returns that we see voxels gain ground as an industry standard.

In the meantime voxels should enjoy dominating augmented reality applications as devices with sensors will naturally generate point clouds. That's where we'll see the first strides in optimizing voxel graphics on a hardware level.

My expectation is that voxels won't be the go-to for immersive full screen photo realism for quite some time. It'll be the choice for mixed reality and games with an retro bent or artistic style which can be accommodated by voxels of not too high resolution.