MASTER SKINS ABSENCE?

Hi,

I noticed that the last three heroes have no master skins!! Does anyone know why? Is blizzard abandoning the concept of master skins in favor of more drastically different themed skins?
Please help.

I didn't find the right solution from the Internet.

References:
eu.battle.net/forums/en/heroes/topic/17616772018
Animated Promos

Thanks