I don't agree with the statement that all cryptos are priced against bitcoin, and that, somehow, if bitcoin went to 0 they would all suddenly be 0 too. Now obviously, if bitcoin took that kind of impossible dive it would safe to assume that all other cryptos would be in trouble too (if bitcoin was worth 0, I'm imagining society itself is crumbling), however, your argument is like saying that if USD went down to being worth 0 in Euros (which again, would never happen), that japanese yen would also be worth 0 in Euros too, which is obviously silly. My point is, these currencies are priced not only against bitcoin, but against other cryptos and other fiat currencies too, they would still have relative values that could be derived even in the unlikely event of bitcoin disappearing tomorrow. Like anything, their value would be simply this: what are people willing to pay for it.