This is just to throw some ideas out.

Kidd isn’t dead, 1, oda rarely kills and 2, I feel oda isn’t done with Kidd.

So here’s 3 ideas and their arguments.

1.	⁠Sea king.

Kid was either be a sea king I heard people saying this as a meme but let’s just play with the idea.  
Kidd was sinking in the ocean so unless it’s revealed he’s secretly a fishman with gills or there’s a secret fishman society below elbaf and he sunk down into a area that has air,  it’s pretty much safe to say something happened to Kidd to get him out of the situation of drowning.  Now it’s been discussed before that Kidd has possible ties to Davy jones and his former bounty before his 3 billion bounty had the numbers 470 in it,  there’s some word play here as 470 can mean Jonah ghost.  Jonah ghost is reference to Jonah from Jonah and the whale which is a biblical story about a man who was eaten by a giant fish for disobeying god.  Jonah is believed to be an origin story for Davy jones.  
Now in egghead we saw the island is guarded by sea kings once of which looks identical to Kidd,  perhaps this is a reference to Kidd being connected to a sea king as if he was eaten by one and is currently inside the stomach of waiting for the opportunity to escape ?

Over all I say this is very unlikely.

2. Shanks ship.  
In egghead as well we saw Demoro black dressed as kidd in jail.  
This might set up that Kidd is locked up somewhere and one idea is shanks for whatever reason decided to rescue Kidd from drowning took him on board and got the red hair doctor to patch him up then they threw him into the brig.  Possibly shanks not wanting to kill kid took him on board in hopes they can patch things up and become friends.  So it’s just Kidd locked in the brig yelling at shanks telling him just wait till he escapes. This is similar to what happened to him and Luffy with kaido who tried the same thing though more brutal when he captured them and threw them in udon hoping he would break their spirits and get them to join his crew.  
This is also a parallel to ace and wb,  ace fought jinbei to a standstill and passed out and woke up on wb ship having it be revealed wb showed up to deal with the man who’s been challenging his people looking for him.  
Ace wasn’t exactly a prisoner but it wasn’t quite like things were smoothed, the only reason ace wasn’t free to walk around was because wb wanted to get him to join the crew and really he didn’t see ace as a threat which was clear as ace kept trying to kill whitebeard on a daily basis only to be smacked away.  Like for one incident wb took a nap and ace jumped out with a knife to kill wb in his sleep only for wb to just smack him throw the wall while still sleeping with the rest of the crew treating this as no big deal and just ace getting his frustration out of his system.  
Shanks might be doing a similar thing here with Kidd.  
He will also be doing the same with barto and likely throw him in next to Kidd.  
This I say is more likely

3.  He’s on elbaf.  I don’t know how maybe it was someone on Kidd crew or a local who forever reason wanted to help but someone fished Kidd out of the sea and he is currently in Elbaf being patched up.  He hasn’t shown up yet because he hasn’t healed.  
Some ideas on who did this.  
A giant.  The giants might have a level of respect for Kidd as he was part of the duo who took down big mom who the giants hate,  dory and broggy don’t share this sentiment cause they were already on little garden when the incident with big mom happened.  But other giants might have more respect for kid and want to help him.  
Urouge, we still haven’t seen urouge in a while so this might be a great way to bring him back and it makes sense cause urouge does actually have a tendency to be around the same area as kidd.  
Urouge introduction was him fighting killer with drake breaking the 2 up. We don’t know the context of the fight and what started it but that was how they were introduced.  
We are then told urouge was injured fighting cracker after he beat up snack when he invaded wci. We aren’t told why he invaded wci just that he did.  But the thing is we also learned that Kidd invaded wci best up snack and stole a poneglyp sketching so it’s a bit weird they both invaded wci and beat up the same commander.  
After that we see urouge recovering on balloon terminal when kaido walks pass him and jumps off the edge of the sky island where he plummeted down and crashed on top of the island Kidd was having a meeting with Hawkins and apoo on.

Now this is strange because this means balloon terminal was directly above kidd’s home base which is another incident of urouge being close to Kidd.  
So I don’t know if urouge is stalking Kidd or something but that’s 3 incidents where urouge is just in the general vicinity of Kidd.

What his motives are good or bad I do not know.

I also want to point out this strange detail but Luffy elbaf outfit includes this red feathery cape which looks suspiciously a lot like kidd’s red feathery cape.

This is also more likely.

Now of all 3 options I feel 1 is the weakest.

3 is probably my best guess.

Other than those 3 I don’t know. It’s not like he could swim to another island and I doubt he actually drowned,  kid is out there somewhere.

Where is Kidd ? 3 ideas