Spoilers ahead for the Season 2 finale of Star Trek: Discovery, called "Such Sweet Sorrow."
Star Trek: Discovery premiered as a show set in a delicate place in the Star Trek timeline: shortly before the events of the original series and even featuring characters from the original series. While that gave fans the opportunity to see characters like Sarek, Pike, and a surprisingly sexy Spock, it meant that there were things Discovery just couldn't do without treading on original series canon that definitely did not mention Michael Burnham or others of the Discovery crew.
Now, the Season 2 finale solved the problem of keeping the Discovery action going but keeping it out of previously-established canon. Fans no longer have to wonder why Spock never mentioned checking in with his sister on the original Star Trek series, for example. The Discovery crew jumped into the future as part of a last-ditch attempt to stop Control from wiping out the universe after gaining sentience.
Now, time travel is nothing that hasn't been tackled before in the Star Trek franchise, but Discovery jumped forward a whopping 950 years, which places it further in canon than any other show or movie. Discovery can truly blaze its own path. Showrunner Alex Kurtzman shared how it feels to approach a brand new time period in the Trek timeline, saying this:
We love playing within canon. It's a delight and a privilege. It's fun to explore nooks and crannies of the universe that people haven't fully explored yet. That being said, we felt strongly that we wanted to give ourselves an entirely new energy for season three with a whole new set of problems. We're farther than any _Trek _show has ever gone. I also had experience working on the [J.J. Abrams] films where we were stuck with canonical problems. We knew how Kirk had died, and we wondered how we could put him in jeopardy to make it feel real. That's what led us to go with an alternate timeline; suddenly we could tell the story in a very unpredictable way. That's the same thought process that went into jumping 950 years into the future. We're now completely free of canon, and we have a whole new universe to explore.
The Star Trek universe is vast, nuanced, and incredibly popular, and Discovery's expansion on canon answered some questions and added more layers to some characters. That said, Alex Kurtzman raised the point that there are challenges in adding to corners of the universe that are already pretty full. By jumping forward nearly a thousand years, the path is clear for the Discovery team to go in whatever direction strikes their fancy.
Alex Kurtzman was also a writer and producer on Star Trek (2009) and Star Trek Into Darkness (2013), so he was familiar with the challenges of adding to canon without telling a story with a predetermined ending. In the case of those movies, they wound up creating and exploring an alternate timeline that was quite similar to the original Trek timeline in some ways but quite different in others.
For example, Khan was still the baddie of the second movie, but Spock was not the one with the heartbreaking farewell to his friends as he saved the ship. (Of course, Kirk came back to life without needing a Search for Kirk movie. Gotta love those Tribbles.) Star Trek: Discovery didn't have to create an alternate timeline to escape the confines of established canon; jumping almost a millennia in the future does the trick!
All of this said, the jump into the future doesn't mean that Star Trek: Discovery will progress without any connections to preexisting Trek canon. Alex Kurtzman went on in his chat with THR to explain:
There will be canonical references to everything that has happened in the various shows; we're not erasing that. But we're so far past that point that all of that is a very distant memory. We're very excited to see how you put the elements of Star Trek in an entirely new universe.
Characters like Spock and Sarek and Pike may not be able to appear in Discovery anymore, but that doesn't mean the characters won't mention them or their exploits. If they have access to the histories of what happened before, they can even reference and learn from the adventures that took place in the 950 years they missed.
Discovery has already been renewed for Season 3, so there's no need to worry that fans will never get to see the new status quo now that the show will be set so far in the future. Alex Kurtzman will have a co-showrunner when the action picks up again on CBS All Access. Discovery definitely isn't the only source of Star Trek coming to the streaming service. The Picard series is taking shape, and then there's that Georgiou spinoff!