There was no death that could have lived up to his legacy, so the series literally airlifted Rick Grimes on The Walking Dead to a mysterious location instead of actually killing him. Although Rick's story isn't really over, Andrew Lincoln won't be in Walking Dead Season 10. But he could return to the universe somehow, sometime soon.
Since the helicopter incident, every character on The Walking Dead has moved on under the presumption that their once leader is dead. The series actually jumped forward six years following Rick's departure in the first third of Season 9. While that's technically plenty of time for Rick to have made it back to his family and friends in Virginia, Season 9, Episode 5 was officially referred to as "Rick Grimes' final episode" of The Walking Dead by the network — which pretty much sets it in stone that the character won't return to the original series. There's no hidden meaning or other way to interpret the phrase "final episode."
Immediately following that very final episode, however, an AMC press release announced that a series of Walking Dead feature films would reveal what happened to Rick next. "The first film will explore the story of where Rick is taken and what he faces in a new corner of the zombie apocalypse," detailed AMC's press release.
"It is really important for the audience to know that we are going to be continuing to tell the story of Rick Grimes in these AMC Studios original films," said executive producer Scott Gimple per Entertainment Weekly. "We don’t want this thing to be like, 'Oh, well, he’ll be back on the show any moment now.' We are telling Rick’s story in another medium." There hasn't been much information about the upcoming films since that initial announcement, but hopefully with Season 10's arrival, fans will get a few more details.
Fans actually already learned more about where Rick Grimes is this summer by way of Fear The Walking Dead. The same helicopters that took Rick away from The Walking Dead showed up on the spin-off series. One of the survivors actually met one of the mysterious helicopter people named Isabelle. While it wasn't Rick himself, the connection did reveal more about what the group he's with is like. Who knows, maybe Lincoln will make a cameo on Fear in the future instead — "final episode" doesn't have to also apply to TWD spin-offs.
As for the original series, Rick's spirit lives on in his daughter Judith Grimes. AMC's official bio for Judith in Season 10 reads that while she has very much been raised as Michonne's daughter, Rick "is a part of [Judith's] daily life as she shares her version of stories she’s heard to keep his memory alive. Her history is never forgotten. She embodies the past, present, and future."
Speaking of Michonne, Danai Gurira is set to leave The Walking Dead next. Now that we know departure from the series doesn't necessarily mean death, maybe there's a chance that Michonne and Rick might see each other again in one of those movies.
If Rick really, really isn't coming back to her on The Walking Dead, maybe she can find him. All that matters is that he's alive and the possibility is still out there.