Well, I'll maybe take a look at it. But to be honest I'm getting smooth 4K playback just fine in Kodi 17 with a four year old silent HTPC. If it degrades in future maybe I'll have an incentive to get involved.
If you're lucky someone will come along and implement EGL streams + NVDEC support in Kodi. It's do-able, but it's unlikely to be someone from Team Kodi.
Doesn't NVDEC support come for free by using ffmpeg?