See, I find this to be the core of what is wrong with the idea of "hard" sci-fi. The technology we have today is magic to a medieval peasant. Just because the explanation of how something works gets disproven, doesn't mean the invention itself won't happen.
Take FTL travel for instance. Sure, lightspeed is a hard limit, but we don't know yet whether wormholes are possible, which meanns warp drives are not impossible too.
But more than that, it's the effect that tech has on people that makes good sci-fi, not the tech itself. In this sense, even the technically impossible remains relevant. For instance, we'll (likely) never meet aliens, but most of us will one day be confronted with the themes of aliens stories, e.g. understanding people beyond our culture, dealing with the unfathomable, grieving our place in the universe, etc. "Hard"ness is just aesthetics.
Take FTL travel for instance. Sure, lightspeed is a hard limit, but we don't know yet whether wormholes are possible, which meanns warp drives are not impossible too.
But more than that, it's the effect that tech has on people that makes good sci-fi, not the tech itself. In this sense, even the technically impossible remains relevant. For instance, we'll (likely) never meet aliens, but most of us will one day be confronted with the themes of aliens stories, e.g. understanding people beyond our culture, dealing with the unfathomable, grieving our place in the universe, etc. "Hard"ness is just aesthetics.