If, and it's a great big if, Oda kills someone off, it's gonna be Kinemon or Denjiro. Kine'mon is if he's going for the gut punch of a death, given his long he's been in the series, his wife and the fact it would come just before the liberation of his beloved homeland. Denjiro's obviously the lesser option.
The two of them have known Oden the longest, have been the protectors of his children, have been the most plot relevant of the Scabbards and are now leading the two armies.
The only reason that it even slightly makes sense for us to be talking about deaths is that Kaido is one of the very few characters who have the clout to pull off being a murderer (in the present day). Along with Orochi who's already a killer, and BM.