No. With the advent of railguns, there will definitely no longer be any battleships. The whole point of letting an armored pile of iron float into the sea is lost, just as it once happened with armored knights.
And it's not about the uselessness of armor, it's always useful. The question is purely economic - one shot of a railgun is several orders of magnitude cheaper than that of a cruise missile.
A railgun is something like a naval "sniper" that fires projectiles at great speed. That is, it will be placed on "sniper cruisers", which will have the main advantage of their mobility and stealth.
For example, railguns can shoot down enemy satellites in low orbit. It is enough to take a squadron of cruisers somewhere into the Pacific Ocean, reach the desired latitude where the satellite flies, and grind it into dust in a few volleys.
It is impossible to reach the satellite with a laser, it is problematic with a rocket, but a bunch of such " space snipers "- please!
Of course - yes. The new battleships will be floating carriers of nuclear weapons. And they themselves will be nuclear-fueled. In addition to railguns, the battleship will also have lasers that shoot down enemy missiles and aircraft at the speed of light. The battleship will be capable of carrying a gigantic number of missiles, several times more than the Peter the Great missile cruiser. And at the same time, possess such armor that the cruise missile will get stuck in the deck or hull without touching the vital organs parts of the ship, and a nuclear warhead that explodes nearby (except perhaps the Tsar Bomb) will cause minimal damage that can be eliminated right "afloat". At the same time, for greater stealth, the battleship will be built using stealth technology and will be able to submerge under water like a submarine and carry a squadron of fighters and several bombers, helicopters and reconnaissance aircraft, as well as a couple of drones. In addition, a modern battleship will be able to hide under historical battleships and sail into any water area like a floating museum and deliver a deadly strike from nuclear missiles and sail away already underwater like a submarine.
Battleships were used in the tactics of linear naval combat, when ships were built opposite each other and were fired at each other from cannons. In modern times, when the fleet has cruise missiles, guided torpedoes, coastal and carrier-based aircraft at its disposal, there is no point for ships to approach the enemy at a distance of destruction of artillery (powder or electromagnetic).