These statements are likely fan service. I have a hard time believing the suits at Sega have any desire to return to this series. Yu Suzuki has even been minimized so much that nobody knows where he is.
Shenmue III would have to be a huge investment in money and development resources. It would take a staff similar to a Mass Effect game with a creative vision that is consistent with the series but progressive enough to fit today's market. If you look at Sega's track record this gen, they are simply NOT that publisher.
As a big fan of the series (ESPECIALLY the 2nd game), I really really reeeeeeeeallyreallyreally want to see III, but I'm also informed enough to know the chances are as slim as Panzer Dragoon Saga Returns . . .