Serenity Caldwell writes for iMore about what happens in year 2 of the 18K gold Apple Watch Edition that a lot of smart people think will sell for something north of $10,000. Specifically, if you had a tech gadget that is a year or two (or three) old but made of gold would you be happy or would you drop another great big pile of money to get the latest and greatest version in gold.
Serenity's post contemplates a replaceable core, which could work but seems so unlike Apple in 2015 that I find it hard to believe. If I had to bet a nickel, I'd say that they'll have a trade in program. The gold in those watches is valuable and Apple could give you a significant discount when upgrading. Also, I'm sure there will be a thriving third party market for those gold edition watches even when they are a year or two old.
Either way, Apple really doesn't have to answer this question until 2016 when they will presumably release the generation 2 Apple Watch.