Why naval railguns may revive larger calibers

Is there a place in a modern navy for guns around 8-inch caliber?

Potentially yes, especially for railguns whose long reach makes a heavier kinetic or explosive payload valuable at the target.

Many railgun concepts examined 6-inch or 8-inch projectiles rather than limiting themselves to current destroyer-gun calibers. Theoretical ranges reached toward a thousand miles, with several hundred miles treated as more plausible. At that distance, a weapon needs either a heavy penetrator for kinetic effect or enough explosive payload to justify the shot. The required terminal effect helps determine the caliber.