9 out of 10 action heroes agree: Repeating a pump-action shotgun looks and feels just plain awesome.
But besides the rule of cool, why would we still use pump-action guns in a future scenario 100-200 years from now? Semi-automatic and even fully-automatic shotguns already exist today. And whether you are fighting a gang war in a cyberpunk slum or get ambushed by a swarm of xenomorphs in an abandoned space station: anything which allows you to kill your enemies faster and easier will save your life.
I've done my homework and found out that today's pump-action shotguns have the advantage of being able to fire a larger variety of ammunition and that the smaller number of moving parts means they are more reliable, more durable and a lot cheaper. But those seem to be engineering problems to me which could easily disappear within a few decades of technical advances.
And that's assuming we keep using firearms with chemical propellant in the future. When we start using electric acceleration (railgun, coilgun...) then we have enough power in our gun to drive the cycling mechanic for our projectiles electrically. And when we go even further and switch to energy-based weapons (laser, plasma, sonic, particles, etc...) then we won't even need projectiles at all.
What technical reason could there still be for guns to have that sweet tchk-tchk BOOM pump action in the future?