Sega is not involved with the development/publishing of Shenmue 3, and apparently getting the rights to Shenmue from Sega was surprisingly easy. I suppose they figured it was easier to just sell the rights to the creator in exchange for some backend as opposed to funding a new game or letting it sit dormant and not generating any money.
http://kotaku.com/getting-the-rights-to-shenmue-was-easier-than-you-d-thi-1712037863
http://kotaku.com/getting-the-rights-to-shenmue-was-easier-than-you-d-thi-1712037863