That answer leads well into my next question then.... Yarn is a drop in replacement today for npm's package.json. Is the ongoing strategy going to be keeping yarn and npm in sync with package.json structure? In other words, if the next version of npm updates the structure of node_modules or package.json, will yarn still move to be compatible with it?

Is yarn a temporary solution to a problem (flattened packages, lock files) or do you see it as the next package manager? I ask because we don't want to put energy into yarn if it's just keeping the seat warm for npm to take the attention back.