A number of fans got a personal photo and message of thanks for a gift they went to him many years ago. It was a belated thanks, and was only a few months ago. he was happy and was clearly working on guyver related things.
It has also been directly said by a personal friend of Takaya San, that there are legal type issues to do with the guyver Manga. I think it was some kind of licensing thing.
It is technically conjecture, but these sources are pretty trustworthy.