People who think it's impossible seem to forget the Straw Hats vs Oars/Moriah, where the gap in strength was arguably comparable to what the current Straw Hats vs Kaido would be now. They also seem to forget that even the scabbards were able to tango with Kaido for a fixed amount of time as well, and not to mention how just Nami, Brook, Carrot, and Jinbei were able to fend off Big Mom.
There is also the prospect of Yamato joining the crew who is currently holding off Kaido by herself. So I see no real reason why the rest of the Straw Hats wouldn't be able to join Yamato in holding off Kaido until Luffy arrives. Especially considering they all see to have been given a multitude of powerups that make them mush more harder to deal with than their preskip Thriller Bark counterparts.
Personally I am on the fence of this happening, as I just don't see how they can all make it up there before Luffy, who isn't that far off from being recovered, and the Calamities have yet to fall. But to think it's impossible, or the Straw Hats are just to weak to hold off Kaido is asinine.