I think many of us thought that the Master "disappeared", to go to the Verum Rex world... but I think the truth is, when the Master and Luxu disappeared... they are actually going to this Unchained X virtual world that the game takes place in, and have these conversations that we are seeing in the latest story updates. The video above implies that Luxu and the MoM both went away, and at some point Luxu comes back.
Also, I think people don't understand how potentially huge this recent revelation on the nature of Darkness is... For so long, we just thought Darkness was there as this like "angry" side of everyone's heart (which it still could very well be), but now it appears to be these invisible beings that only want to seek out the desires of individuals, and make them happen... or they are just being coordinated by someone, and they are just giving us vague answers that won't be all that helpful. Darkness states that there are more beings of Darkness, then there are of light... interesting. Darkness also was "old friends" the MoM, but doesn't need him/work for him, it looks like down on humans for some reason, and is usually invisible except for right now.
I know many of us were already operating on the assumption of Darkness in people's heart/Realm of darkness is different from these "Beings of Darkness" who wish to act upon and manipulate the desires of people they see (at least so far as they have explained), but what if they really are one in the same? If that were true - what impact would that have on the conclusion of things in Kh2: that all darkness is natural, and half of what makes our hearts work, and we need to just accept it. If that's true, than at some point living people were pure light, and accepted these beings of Darkness, and we then had to learn to reign in our inner darkness, which only wants us to pursue our own betterment (easily translatable to the deadly sins) in order to keep worlds and people from falling completely into darkness. Why Darkness ACTUALLY exists (besides the not so helpful "if there's light, there's always a shadow" explanation) seems to be that it came OUT OF people who had pure light... but had desires for more, more light... and for some reason that manifested into actual dark beings? Darkness hearts pure light... probably because they have no desires for them to exploit and plant themselves within. Still, Darkness seems to speak lowly of humans... Yet it looks like Darkness constantly looks for hearts, and use their desires to infiltrate them.
Potentially, Darkness once always existed INSIDE of light, and light PUSHED that part itself out, in order to prevent war and pain, which it saw happening. As such, Darkness is like this completely shunned part of Light, that is just as important and old as "light" itself, and it really took until the modern Sora era for everyone to realize that trying to avoid darkness just made it stronger and could never actually stop it.
Still, we know the MoM goes to the Verum Rex world at some point. So there's still a lot more to explain.