I haven't been following closely enough to know what the obstacles are, but I wonder why some of these vendors don't experiment with wider system memory buses to increase the bandwidth along with these iGPUs gaining more interesting cache and IO topologies.

My memory is that we used to see more variation with single, dual, triple, and quad channel memory configurations in essentially prosumer/pro desktops. But lately, it seems like everyone has just stuck to dual channel and minor variations in memory timing of the same DDR generations.