Now Imagine being the boss of the straw hats. If you HAD TO REPLACE 2 of its members who would you have done so and explain? Also, mind the fact that if you are replacing a certain position you also have to take a person who is from that position. For example: If you are replacing a cook then you also have to take a cook (you have to replace them there's no choice
I would have gone with these takes
Usopp - Van Augur ( His Devil Fruit is OP it is like a taxi cab and will help straw hats to escape from danger (and to prevent Zoro from getting lost)
Franky - Rayleigh (He has a vast knowledge of ships and can help the Straw hats to learn Haki. He will also help Luffy attain his goal of becoming the Pirate King since he was the first mate of Roger)