In the founder's writings, there are numerous places where he attributes learning directly from the kami. Although he didn't mention kami, Minamoto Yoshitsune learned sword fighting from the tengu king Sojobo. Musician and poets ascribe their inspiration to their Muse. In all these cases the creative person describes a spiritual persona outside of themselves. Today these inspirations might be described as the product of the subconscious revealing itself to the conscious mind.
When the founder writes about the kami entering his body, he is describing possession. Shinto is a primal, shamanistic religious practice. Learning through spiritual possession could be one aspect of spiritual practice.
Now we have two sources of knowledge from O Sensei's spiritual practice:
- Learning directly from a kami and/or other spiritual persona.
- Possession by a kami and/or other spiritual persona.
When we take your list of names that are described as following the founder's spiritual practice, we need to eliminate everyone who is not devoted to Omotokyo. This is not to discount any other spiritual practice, but to acknowledge O Sensei's devotion to this particular Shinto sect.
From this shorter list we need to see who has followed the core of the founder's practice of learning directly from a kami and/or other spiritual persona. To my knowledge no one has made such a public declaration. Additionally I have not heard of one person on the short list, who has been possessed by a kami and/or other spiritual persona.
This leaves us nobody whose spiritual practice matches that of the founder. Aikido already has one founder, why be greedy and want more?