Reasons:
1. Kidd is One Piece personification of true grit. His devil fruit being able to bring scrap parts together after total and utter ruin is literally the personification of this sheer tenacity. His clash with Red Hair only made him stronger.
2. Kidd's departure from the story is very sudden. It's simply not Oda's style. If he wants to write Kidd off from the story, he would've given him more focus in the early post timeskip arcs like Law. He didn't, which means he's being reserved for something greater.
3. Oda said he had plans for Kidd. Using him as "hype" fodder for an already well-respected character in the fandom is not a plan. Not even bad writers would brainstorm such nonsensical story beats.
4. Kidd's childhood is a big unknown. Shanks seems to be interested in the fact that he's from the South Blue. His SBS backstory does not delve into his childhood, it's barely his youth years akin to Luffy/Ace/Sabo backstory. We still haven't seen Kidd's edition of a "Corazon, Kuina, Zeff" backstory. We still haven't truly seen the very core of Eustass Kidd.
5. Kidd's resemblance to Shanks is way too great that it's almost uncanny. It can never be unintentional. His encounters with Shanks and the Red-Haired Pirates is also way too frequent to be random. Oda is hiding something. Shanks might not be as a good a person as he seems to be. Kidd's temporary defeat will reveal this truth soon.
6. Time and time again, Oda portrayed Kidd as Luffy's equal and true EoS rival. In Sabaody, in Udon's prison, in having CoC, in having a Right-Hand man supernova. Kidd is being written as an important anchor to Luffy's overall character development not some "hype" fanfic fodder.
7. Oda does not kill off his characters, let alone drown devil fruit users, let alone entire crews in non-flashbacks, let alone kill them by seemingly good people, aka the giants.
What to expect in the next chapters?
Kidd awakening his VOAT in the depth of the ocean, mirroring Fraudfy's Wano scene. With one arm, he grabs his right-hand man Killer as the waves carry them ashore to a nearby cavern. There, him and Killer grief for their dead nakama. They reminisce what made them seek the One Piece, destroy the World Nobles, and the Rat-Haired Fraud. *cue Kidd full backstory* In an awe-inspiring training montage, Kidd unlocks his Advanced CoC thanks to his Haki blooming from fighting Lanks. As MC Goofy arrives at Elbaf, Kidd exits the cavern and finally launches his counter attack. Goofy watches his father figure gets pierced by Kidd's AdvCoC coated Damned Punk. He gets mad and uppity, crying like the pirate twink he is while seething at Kidd's fresh yonko catch. The race for One Piece enters its final stages. Cryfy vs Punished Kidd (with BB already being defeated in Egghead).
