Anyway it's sure that Kaido and Linlin's alliance will be ended before and during the final battle, that isn't happening on Onigashima.
The alliance can't take on and manage to beat two Emperors at the same time, and the unstability of a partnership between members of the Rocks Pirates and these two in particular have been brought up too many times for anyone to truly believe that it will last until the end of Wano without a betrayal.
And I have the feeling that Perospero hasn't given up on his idea of ending the alliance between his mother and the King of Beasts, and that since his mother refused his arguments to renegade her partnership with Kaido that he will instead decide to use ruse and manipulation to reach his goal.