Likely impossible in practice. None of the design decisions in X core make sense any more (it is designed for a world where 2D acceleration was important and didn't design for this world we live in where the kernel controls all the hardware). The parts that matter are extensions and hacks on top of that. All the developers (we're verging on literally all of them) who had to work with X fled it like rats on a sinking ship.

Signs suggest it is genuinely unmaintainable. The only problem is the replacement was secured against common user tasks being possible and un-securing it has been a long, slow and painful process of community negotiation. Although we're probably most of the way there by now.