The disks are going to be called BluRay Ultra HD. That's going to be the official name in the shops. 4K relates to the player.
Not surprising that Sony are pushing things as they invented BluRay. The PlayStation 4 will support 4k movies so expect a big push once that comes out later this year.
And consumers won't be buying them.
Sony did not invent Blu-ray. You really don't know anything about it as the last few posts show.