(I.e., can this special Apple Gold(TM) be melted and reused like regular gold, or does it just go in a landfill after two years like every other apple product?)
It's funny to think that in 20-30 years there may be a cross section of retro-computer enthusiast/gold watch enthusiast. Who'd have predicted that?
The iWatch would be lighter as a result of using this new technology. This reduces the value of the Gold it contains, but increases the iWatch's quality as a techology device.
Will this be possible with Apple gold? Maybe, but it sounds like the salvageable quantity from a watch band will be enough to make a ring, not another watch band.
My old 3GS is still doing good service for my father in law, and my 2006 iMac only packed in last year. My parents are still using my bought-on-release iPad 2 and 4 years after release its running the latest iOS 8. In my experience the useful lifetime of an Apple product is typically about 6-8 years.
Apple has let you bring you old devices in to be recycled in the past however; Maybe they could extend this to buy back old watches? People have envisioned some upgrade program, though I'm doubtful Apple would be too concerned with melting down old watches for their gold.
I'm sure Apple could buy back, clean, and reuse bands from obsolete watches, but they might be the only buyers if iGold is too difficult for a regular jeweler to work with. It will be interesting to see if one of Apple's first moves on entering the jewelry market is to hamstring the independent secondary market.