I dunno man. I think there might be a lack of understanding when it comes to how manga is actually created.
Takaya may well have had somebody else writing the story, or drawing the names for him, but when such a person isn't credited, it makes it all the more easier to replace them without drawing attention. If the series has been cancelled, his publisher would very likely announce the fact. If he is lacking some kind of creative direction regarding the story narrative, his assigned editor would help him with that.
We know he was advertising for an assistant, but such adverts are 99% of the time for assistance in drawing backgrounds, clothes etc. I think, whatever the reason is, it's more than likely a personal one that has really snuffed out his desire to continue the story right now. I'm usually quite despondent when it comes to this thread, but his publishers obviously want to see it resume, and if there's any way they can help him along regarding creative assistance be it art or narrative, you can be sure they are doing what they can. I'm hopeful he'll back, but he obviously has other bigger fish to fry right now I guess....