Rick's Death Gives The Walking Dead A Fresh Start
While there are many reasons behind The Walking Dead's steady ratings drop over the last few seasons, one is just that the show's formula has arguably gotten quite stale. Some of that is due to repetitive writing in general - survivors find sanctuary, sanctuary isn't what was promised, they have to leave and look for new sanctuary - but some of it is also specifically related to Rick. As mentioned above, when in doubt, TWD's writers seem to fall back to showcasing Rick. After eight seasons - and with the wealth of characters available to the show - it's time to freshen things up by presenting the zombie apocalypse through different eyes.
Along with the reports of Andrew Lincoln's impending Walking Dead departure came news that AMC was apparently offering Norman Reedus (Daryl Dixon) big money to stay on and take over as series lead. While Daryl hasn't exactly been the most noteworthy of characters the last few years, he remains extremely popular, so it's not hard to see why AMC is looking to him to step up. That said, Daryl is also closely associated with Rick, and if The Walking Dead wanted to truly reset itself and feel like a new show - albeit with many of the same characters involved - it might be wise to introduce a new lead character, one completely new to the ongoing storylines.
Said new character wouldn't even necessarily have to be someone from the comics. As mentioned previously, The Walking Dead TV series has deviated from Kirkman's printed work in many ways, and there's no reason an entirely new character couldn't be invented to lead the show. For example, Daryl himself was created specifically for the small screen, and that's never impeded his popularity.
Killing Off Rick Raises The Stakes
For about as long as The Walking Dead has been on the air, it's been known for being quite willing to kill off its many characters for dramatic effect, often in incredibly surprising and/or upsetting fashion. One need only to remember Glenn and Abraham's skull-crushing demise at the hands of Negan's bat for proof, or recall when Denise got take out with an arrow through the eye out of nowhere by Dwight. Yet, this "anyone can die" philosophy has often failed to extend to the series' core characters, with Rick never really seeming likely to meet his maker at any point so far.
While Rick's death itself likely won't be surprising - after all, we all now know his actor is leaving the show - it can definitely happen in a surprising manner, and at the hands of someone fans wouldn't expect. Maggie (Lauren Cohan, who herself is only currently contracted for part of Season 9), vowed to show Rick the error he made in letting Negan live, and it would certainly be shocking to see the two old friends end up battling to the death. A perhaps even more intriguing option would be to make Rick's death exceedingly mundane, to illustrate that sometimes death just happens, with no real reason behind it.
Regardless of how it ends up occurring, Rick Grimes dying forever ends the idea that any character is safe from death in the world of The Walking Dead. No matter how protected one might feel at a given moment, the reaper could be lurking behind every corner, ready to end one's life in an instant. The specter of death has always been a close companion to those "lucky" enough to survive the arrival of walkers, but if Rick loses his plot-armor, anyone can. A post-Rick world could end up being an extremely exciting time to be a Walking Dead fan.