Never

The great Roger Clemens leads active players with 46 career shutouts at age 44. Among the younger guys Mark Mulder at age 29 leads the way with 10 shutouts. While baseball's changes have led to homerun records falling, they have made pitching records more and more unattainable. We celebrate milestones for pitchers these days, but I'm not sure there will be many all time records broken again.

Extremely unlikely, unless Johnson himself rises from the grave and gets to face  Pittsburgh 111 straight times....

the way that managers use their bullpens these days, we probably won't see pitchers with 110 complete games, never mind shutouts.