Kizaru won't be a major antagonist in two arcs in a row, that's extremely unlikely.
Literally the only candidate is Ryokugyu. There cannot be a competent team up of CD + Fuji since Fuji wouldn't support any of the things they're already doing like kid hostages.
Gigabull is absolutely perfect and even fits perfectly into this arc when you consider the landscape and Gigabull's ability.