Before you can do that you need to secure a method of transport--one that can hold everyone in the session. The gravedigger estimates the population of the Medium at about 100,000, which seems bizarrely small considering it originally contained six (seven?) inhabited planets.
(The only way you're going to get everyone off Skaia is if destroying the Dark Planet does in fact "restore its memories." You think you'll collect everyone else first before you try destroying a planet, though. You don't think even a transcended Dreamer should be able to destroy a planet.)