I agree that we don't know the answers to these questions, but I don't agree that they outweigh the awful, terribly sucky thing which is death. I don't want anyone to die ever again. That people have died a few times since I started typing this is really, really bad!
Look, if you were designing a society and were trying to make the tradeoff of whether people should die or not, how would you weigh the arguments for and against death? "Hmm, on one hand, old ideas die off, so society might progress faster. On the other hand, we will snuff every conscious being out permanently, and they and their family go through years of suffering. Which should we choose?" Are you seriously arguing we would choose the former?
I don't think they allow, expect, or calculate an unbounded positive as t->infinity. I don't expect we'll get caught in a local minimum - we've done a decent job breaking out of them when the individuals involved haven't had nearly as much at stake...
Look, if you were designing a society and were trying to make the tradeoff of whether people should die or not, how would you weigh the arguments for and against death? "Hmm, on one hand, old ideas die off, so society might progress faster. On the other hand, we will snuff every conscious being out permanently, and they and their family go through years of suffering. Which should we choose?" Are you seriously arguing we would choose the former?