I would love to see all the SH getting individual fights, and they dont even need to fight a specific group of the Beast pirates, they could fight Numbers, F6, Orochi subbordinates even pehaps some of the BM pirates more in the future.
But unfortunately i don't think they will have this fights, there to much characters in the alliance, and i think Oda will give Law, Kid, the Scabbards, Marco and Yamato more time to shine than some of the SH.
Pehaps from the weak six just Nami(that got the Zeus power-up) and Franky (that is with the Shogun) will have proper fights.
But if the numbers happens to have some different power than just being giants brawlers, could be that Oda will give some SH the mission to deal with them.
Could even duo fights, with Ussop&Chopper, Franky&Brook, Robin&Jinbei, Nami&Carrot* and them Luffy, Zoro and Sanji getting individual fights