my question is, does the electric bass really have to 'evolve' any further? have the violin, trumpet, saxophone, flute, tympani, cymbal, grand piano, cello, clarinet, etc. evolved any further? personally, i do not believe that the most desirable ones have.
Have to? Naw. Nothing "has to"...
On the other hand, most of the instruments you cited have evolved over what is probably 200 years - or longer. We don't usually think of them in those terms, because virtually all the major innovations were completed long before any of us was born.
The electric bass, on the other hand - at least dating back to Leo Fender's first prototype - is scarcely 60 years old. And in that time it has evolved significantly - driven by rapid changes in music/instrument technology - as well as by rapid changes in music itself. Hardly an accurate comparison.
Are there still people who play the harpsichord? Sure. But not nearly as many as play the piano/organ/synth.
Are there still people who play the lute? Sure. But not nearly as many people as play the guitar.

MM