But at the end of the day, if we are growing that's all that matters, because it means there are more people today than yesterday so that is the only thing that we should be caring about. I get that it is not going to be all that crazy or be any great, but we could make that work one way or another.
Imagine a situation where the whole world is using it right now, for everything, there are no more fiat currencies and we all use bitcoin, the transaction times would ruin the whole world, and the costs would be insane. Hence, we need to fix some stuff before we start to think about this. Lost coins do not mean anything at that point, because we have other stuff to think about, lost coins just makes the price go higher, that's all there is to it, nothing added on that, it is what it is.
Lost Bitcoins isn't an obstacle; I'm expecting to have lost anywhere between 0.05 and 0.10 BTC myself—not a noteworthy amount in 2014–2015, but it's still a reasonable amount of money nowadays. Lost Bitcoins limit the available ones, leading to increased rarity and, thus, higher prices since the available supply is lower than the 21 million.