At a high level, The Dao is like Pokemon. Casual observation suggests that it may be a more or less consistent world internally and that a lot of people are very excited about it. A few of those people even claim to fully understand how it works. But there's a lot of fat guys with acne blindly spending on Pokemon cards thinking it's a wise investment.
Unfortunately, the fans are so excited that they jump up and down clapping all the time and forget to breath while they're talking. This makes it very difficult to understand what they're trying to say. If you manage to understand, you will hear something like:
"Most Pokémon have only one type. However, EX Team Magma vs Team Aqua introduced Dual-type Pokémon, which have two different types. For a while, all existing dual-type cards had either Darkness or Metal as their secondary type, with the exception of certain Pokémon cards with the Dual Armor Poké-Body, such as Medicham from the EX Crystal Guardians expansion, which can have multiple types when certain energy are attached."
Now what possibly happened during the attack is that Pokemon cards are spontaneously catching fire! This is particularly troubling, because Pokemon just came out with a super-duper fire defence card and told everyone to buy it for lots and lots of money. And everybody did.
Now while all of this is clearly very troubling for heavily invested Pokemon fans. But in the grand scheme of things, well a butterfly flapped it's wings in China: there's a theoretical possibility that this affects anything, but in practice no one but fans cares.
> - How does ethereum "go missing" in a distributed blockchain, where you can see all the transaction endpoints?
1. keep the exp you earned 2. lose some money 3. wind back at the pokemon center at the pokemon league 4. have to start over on the e4
> Who loses and who gains from an attack of this scale?
Pokemon fans, obviously.
> How severe could this attack be - does it pose an existential threat to The DAO (or Ethereum, more broadly)?
Synchronoise when used by Pokémon like Umbreon. It deals damage to every Pokémon that shares the user's type, so in Umbreon's case it hits every Dark type Pokémon. Only it doesn't, because it's a Psychic move and always fails.