Could railguns bring back armoured gunships?

Could a heavily armoured, big-gun warship become practical again?

Possibly, if mature railguns or Gauss guns make high-velocity saturation fire substantially cheaper than missiles.

The idea depends on successful railgun or Gauss-gun development. If electromagnetic weapons could reliably launch very high-velocity shells, each shot could cost much less than a missile. A ship might then exploit volume of fire to saturate an opponent instead of matching expensive missile for expensive missile. This is an economic and technological test for a future gunship, not a prediction that battleships will necessarily return.