It's saying pages will be uneditable by October, I'm pretty sure, and as soon as what little money remains runs out, the site will go dark. They said they're keeping things on as long as possible past Oct so that wiki owners can back things up, but something must still be done with that backup eventually. The sooner a new site gets chosen, the sooner things can be ported over, and the less chance there is of missing the opportunity and losing data. Ideally, it'd be best for the new wiki to go up while the old one is still accessible, just so people can make sure everything made it across safely and nothing got jumbled up or lost in the shuffle.