there are some really good suggestions here about ampflication. like wireless amplification on your hip.. but electric bass wise, i very much doubt there is any more you can do to a bass guitar to make it any better, there are guys making basses at the pinnacle of instrument making. yeah there are string through bodies, high mass bridges, headless basses, .. dont get me wrong, there all cool in my book but it always seems like over kill to me.
i like a good preamp, but a preamp can really make a difference in your sound. a string through body wont. neither will a headless bass.
i can understand the zero fret, and i can understand PLEKing, but these are all minor tweeks to the wheel.
instrument making only really needs a certain amount of perfection. the innovation or music, comes from the artist in his or her music. how many times can you innovate the wheel, to drive it, how many times can you innovate a bass guitar, its a sum of its parts. dont get me wrong i love talkin bass, but it gets a bit neardy sometimes.