Some altcoins stand on their own, they don't rely on Bitcoin, so if Bitcoin crashed down to 10$ there will surely be some turmoil but Ethereum will switch over to the 1st on coingecko and CMC, many altcoins including Ethereum will lose their value but the strong ones will be cut off from Bitcoin and Bitcoin will die, it will also take a long period of time before things settles.
Well, that sounds like an interesting scenario to be covered by your flowers but I'm not sure it's correct. Bitcoin brought a revolution by blockchain, will the market in ETH easily meet the demand then? Personally, I think the path for bitcoin to drop to $10 is pointless and almost 99% realistic of it will not happen. and we probably wouldn't expect too much in this situation.
if it will going to drop that low then lets admit that the crypto is a nonsense and will die together with bitcoin because what is altcoin if there is no Bitcoin around? because dropping that low means there are no support from the people and there is nothing to continue.
but the good thing is what we do believe and that is 10$ for bitcoin will never happen for sure.