In Dengeki PlayStation, an interesting tidbit came up. Gusts Junzo Hosoi, who produced Atelier Ryza: Ever Darkness and the Secret Hideout, noted that the developer could bring Ryza back to be the lead for the next game in this possible series. To be specific, Hosoi compared it to maybe being like the Harry Potter series. While it might be an unfamiliar idea for Atelier, it would work rather well for a possible Atelier Ryza trilogy.
Source: N4G PC Atelier Ryza feels like an alchemist who could successfully lead multiple games