It will mean that @-notifications are finally working consistently, which will have meant that the Quora product design/design/UX team are actually paying attention to long-standing user requests. Prioritising them, even.
I think what would happen next is a well-functioning and more granular Stats page, a tamed and sensible Quora Content Review Bot, a Quora internal search with adequate retrieval, and raising comments to first class objects in Quora.
I would also expect to look out the window and see a squadron of pigs fly past in formation….