Upload & Sell: Off
I don't agree that they're different scenarios because of VR or full frame coverage. At the time of the 18-70mm's release, virtually nothing had VR except telephotos, and full frame DSLRs weren't in wirespread release. Heck, the 5D, which was the first full frame to bring that sensor size to a consumer body, wasn't even released until a year after the 18-70mm came out.
The value of the 18-70 was down long before the 16-85 came on the market, with the latter simply worsening it. It suffered from the same fate as most kit lenses: many/most people buy a body with a kit lens, and enough eventually outgrow the lens, either regressing to super-zooms for many consumers, or to more expensive gear for the enthusiasts - leaving a large number of used lenses around. It's just that these more expensive kit lenses have further to fall than their 18-55mm counterparts.