Once the 4K files will be made available in the year 2015, all the video players will be updated to support the files. Basically, nothing will change, except the bitrate, resolution, etc. The MKV will remain the most viable solution to keep the Blu-ray support. You won't need a specific application to play these files. VLC or any other player with Matroska codecs will play the file. It's required to have a very powerful graphics card and CPU. You can obtain video players through Mac Informer.