Just normal depreciation for the model, as you might expect from any model that has been around in the same generation for the last 5-6 years.
A newer, fresher, higher-tech model of any car will affect the value of the past generation to some extent, but this goes on with just about every car made.
If you want to know the kind of depreciation, just look at prices for 2012, 2011, 2010 versions of the C70, and that should give you a pretty good idea.
Ditto for the Eos.
this might be a good opportunity to buy a C70 at a very good price.