It's not so much the instruments themselves, but the role they play. For instance, a bass typically provides harmonic underpinning and rhythm. Organ pedals, tuba, piano and guitar can be readily substituted. For most groups you want an instrument for chords/harmony, a solo instrument for melody and some kind of rhythmic element. Good keyboard players can do all three at once. Great guitarist can also do the same. In groups it really depends on what you're trying to do as to which instrument does what.
BTW, Nat Cole dropped the drums to get a more elegant sound. He was trying to get away from jazz as a dance music.
BTW, Nat Cole dropped the drums to get a more elegant sound. He was trying to get away from jazz as a dance music.