What do you think of shields? With railguns and etc, normal cover isn't half as effective. So a large shield mounted on one arm could be effective, right?
Hell no. Anticipating projectiles traveling faster than bullets is impossible. There's a reason why soldiers just armor their vital areas instead of holding shields made of kevlar and that's because you don't know you're being shot at until the bullet hits you or flies past you. And if this isn't a person we're talking about but some kind of tank, why even have a shield? Just give it more armor and eliminate the complexity of some kind of waldo, slaved to a sensor suite, holding a metal shield. Also, if "normal" cover can't save you from this purported railgun, it begs the question: why would a shield do any better? And if the shield IS strong enough to deflect a railgun round and light enough to heft on one armor, why aren't you just wearing a suit made out of whatever the shield is made of?
Well, why didn't knights in ye olden times just wear two to three inches of oak over their bodies?
A shield is concentrated armor you can face where you need it to face. Especially with the advent of AI for personal soldier use which can react and track incoming projectiles much more quickly, or at least say 'oh yeah there's a dude to your right', shields could find a use. Other reasons for not having a shield certainly exist, such as it blocking vision, slowing you down when cover would typically be a lot more effective means of protection (improved armor means the cover just needs to bleed off enough energy so it doesn't penetrate), but 'unable to actually protect you' isn't necessarily one of them. It's why it's a big shield; you can't bring it up to block in time, necessarily, but if you're already in combat and have it facing where they're shooting from, and especially if your gun has it's own camera system it can feed into your helmet so you can fire, then it's a much cheaper way of having a good chunk of armor without gaps in it as there would have to be around your joints, that you can pick up or set down as needed, and can direct to the direction it's needed most(admittedly, armoring your front and just turning towards the enemy would also function like this, but you get the idea).
Though, really, true deflection is unlikely. Probably end up kinda like that cover; might twist the projectile's path a bit, bleed off some energy, so it doesn't fully penetrate your armor, but other than that...I mean, a railgun is unlikely to be a basic infantry weapon, simply because of maintenance costs in comparison to coilguns and the like, but still.
I still like idea of melee combat becoming a thing with boarding actions and cramped spaces in ships, and the whole 'projectiles in pressurized environment=bad' thing. Unlikely to actually occur, though. Would require hefty defenses that outstrip offense significantly.
Speaking of which, what do you guys think actual laser 'rifles' would look like? Oversized hand mirrors?