Without Carl Grimes, The Walking Dead's Whisperer War storyline will be hugely altered.
Despite showrunner Scott Gimple promising the AMC series will tell Carl's stories from the comic book source material with other characters, the Whisperer War story will be most altered by his absence. After all, much of the war's launch is fueled by Carl's relationship with Whisperer leader Alpha's daughter Lydia.
Early on, before the war begins, Carl developed a relationship with Lydia -- who has defected from her mother and group in favor of shelter at the Hilltop. Lydia was not interested in the savage, barbaric way of life the Whisperers had chosen and wanted something more civilized. In fact, Alpha is forced to show up at the Hilltop with a pair of hostages whom she would exchange for her daughter, only to prompt Carl's following of the group to ensure Lydia's safety for his own peace of mind.
Lydia and Carl's relationship, which quickly becomes romantic (including a moment where Lydia licks his scarred eye socket), is only one of the many factors in the Whisperer War story involving Rick's only son.
A huge factor in Negan's post-All Out War story arc is his relationship with Carl. While Negan ultimately evolves from his selfish ways in favor of helping Rick lead his people and win the war against the Whisperers, the villain spends a lot of time in his cell talking with Carl. The conversations help influence his turn from villain to anti-hero (at least, so far) and ultimately lead him to be one of the most important factors between Alexandria and their new enemies.
Without Carl, The Walking Dead TV series will have find an all new way to both influence Negan's decisions and development and the Whisperer leader Alpha's outlook on the communities. Should the character be accurately adapted, she will despise the communities for their civility in the first place but the tension built by her daughter's wish to reside at the Hilltop with Carl will be completely eliminated.
The Whisperer War story is the only truly fleshed out major arc in The Walking Dead comics beyond the All Out War story as the New World Order arc is set to play out in 2018. Several other arcs have been infused into the source material both before and after the issue #157 to issue #162 arc but it has been the biggest since -- and will require significant altering if it is going to come to The Walking Dead TV series without Carl.
The Walking Dead returns for the second half of its eighth season on February 25, 2018. For complete coverage and insider info all year long, follow @BrandonDavisBD on Twitter.