How practical rail guns could reshape surface combatants

If rail guns became practical enough to shape warship design, how would fleet composition change?

The carrier-and-escort structure would probably survive, but surface combatants could carry more large guns, lasers for close defense, and only longer-ranged missiles; a sudden breakthrough might briefly trigger a Dreadnought-style rebuilding race.

If rail guns simply replace powder guns, fleet composition changes little: carriers still supply the task force's aircraft, and anti-submarine helicopters remain useful. Lasers could take over close and point defense, but the Earth's curvature restricts their ability to engage sea-skimming missiles at long range. A hypothetical rail gun reaching 500-600 miles would move ordinary land-attack work into the gun's reach and encourage the purchase of missiles with substantially longer ranges. Those missiles could still attack nearer targets when midcourse retargeting or a more elaborate approach was needed. Laser defenses might also encourage twin or multiple-gun mounts that put more projectiles into each salvo. A sudden breakthrough embodied in one ship could trigger a Dreadnought-like building race, with older missile ships retaining useful secondary roles. Gradual adoption would instead change the weapons fitted to familiar fleet formations.