One technology area that's overdue for a good idea is loudspeakers. If you look at a speaker objectively, it's pretty crude--very inefficient, limited in the range of frequencies it can reproduce, delicate--it's made of paper! Certainly there must be better ideas out there to move air. Piezos may be a first step, and I've read about thin speakers and vibrating membranes, but don't know of any commercial products.
Similarly, magnetic pickups are due for an upgrade. The signal they produce is tiny and prone to noise, plus the magnetic field can interact with the string if it's too close. What about optical sensors? There are several out there already that offer better sensing of the string's vibration and are immune to electrical interference from lamp dimmers and other devices.
Digital signal processing offers some exciting possibilities to make a guitar a better instrument. Here I'm referring to something like the Antares auto tune circuitry that does pitch correction on the notes you play so the guitar plays in tune when it's not, and intonates perfectly. It doesn't have to change the sound of the guitar, although it can (like making an electric sound like an acoustic). But think of the restrictions this removes:
- the 25.5" scale length of a Fender is critical to its sound, but if you may prefer the 24.5" scale of a Gibson there was no way up until now that you could get the tone
- intonation doesn't need to be perfect on the guitar, so you don't need a Buzz Feiten tuning system or Plek setup
- transposing a song won't affect the chord voicings
So as the calendar clicks off one more year, I'm wondering what the future will bring.