This article contains spoilers for Star Wars #20.
Recent Star Wars comics have shown how the Jedi Order can always be rebuilt. The history of the Star Wars galaxy is essentially one of conflict - between the light side of the Force and the dark. Typically embodied by the Jedi and the Sith, the two aspects of the Force have waged war for control of the galaxy since the dawn of time. And whenever the Sith dominate, they attempt to destroy all trace of the Jedi.
This is why the history of the Jedi is so incomplete and poorly-understood. Order 66 wasn't the first Jedi Purge; rather, it was the latest, for whenever the Sith dominated the galaxy they tried to extinguish the light of the Jedi. Palpatine followed the typical formula, slaughtering the Jedi, sacking their temples and destroying their Holocrons. After his defeat, it took Luke Skywalker years to collect sufficient information to feel confident enough to reform the Order. Rey will be in an even worse position, because she must rebuild the Jedi after two Purges in quick succession; she has the sacred Jedi texts Luke took with him to Ahch-To, but that's about it. For all that's the case, though, Star Wars #20 - by Charles Soule and Marco Castiello - reveals that no Purge can ever extinguish the Jedi.
Star Wars #20 sees Luke travel to a Force vergence, a world rich in the Force called the Living Sea of Gazian. The entire world is a gigantic living organism, one that takes an imprint of the mind of anyone who visits it, reproducing them exactly as they were at the moment they were on the planet's surface. Countless Jedi have traveled to the Living Sea of Gazian, learning from mentors long dead and leaving a copy of themselves there for future generations. Every Force vergence serves a purpose, and it's quite easy to deduce the Living Sea of Gazian's: it exists to ensure the light of the Jedi can never be snuffed out. Even if all traces of the Jedi are gone, if all records are lost and the history books rewritten, a Force-sensitive need only set foot on Gazian and they can learn all that history and lore once again.
It's interesting to note that, although Luke Skywalker learned of this from a Holocron of Master Yoda he had recovered during his travels, there's no evidence the Empire ever knew of the Living Sea of Gazian. The Force vergences numbered among the Jedi's most closely-guarded secrets - for understandable reasons. The Sith weaponized Ilum and transformed it into Starkiller Base, while Palpatine coveted the power of the World Between the Worlds that he could potentially gain access to through the vergence on Lothal. The Living Sea of Gazian must have been a particularly crucial secret, because its knowledge ensured the Jedi could already return.
Looking to the sequel trilogy, Rey will clearly need to rebuild the Jedi Order after Star Wars: The Rise of Skywalker. She has Luke Skywalker's collected Jedi texts, but in truth she could use other mentors; and Star Wars #20 has clearly revealed a way she could learn more of the Force and the Jedi Order. What's more, because Luke was one of the Jedi who visited the Living Sea of Gazian, there will always a copy of him there - so Rey could even learn from Luke again, as the Star Wars saga continues.
