Well, I think there is going to be a BIG difference between 1 and 2 years.
that said, in 1 year, I think a sport 42MM might sell for about 275$, and in two years probably closer to 175$, a more than 50% price cut.
I think the price cuts on the SS watches might be just a tad higher, but not much. What is interesting in the higher watches is that the BANDS may hold some real value, assuming they can be repurposed with whatever apple watch 2 form factor occur. If they do, then the watches overall might be able to carry some added value for longer.
But, this GEN 1 is going to depreciate pretty darn quickly. you have to think of it that way.
The battery apparently is rated for 1000 cycles, and the way the watch is MEANT to be used, that means just under three years and it's bye bye original battery life.