It appears that Comcast is prepping for the 4K era finally on its pay TV network and is now listing something called the XB4 DVR on product support pages for X1. This is likely to be the Arris supplied XG1v4, a six-tuner 4K DVR, says Light Reading. Comcast has never been keen to arrive early at 4K due to the strain it may place on its cable network for little benefit but it may now be ready to launch its first 4K-capable DVR. Comcast has made limited number of on-demand titles available in 4K for X1 users using Samsung TVs. Comcast has always said that its 4K push, when it came, would include High Dynamic Range, so expect that too.…