Did read about the new feature LOD for the game engine. I ask myself if it this could be helpful to maybe rendering massive geometry scenes outside the game engine. No idea if this makes sense but here is a setup how it works without the game engine.
I used a distance driver for the subdiv value. Key 1 value defines the steps of LOD (Frame should be 0) and key 2 frame value the distance in units when LOD starts(Value should be 0). Think this works with Multires Modifier too.