One gent up in VA that I've known for a few years, thru a common interest in electric vehicles, used to work for GE in their electric vehicle department before "Neutron Jack" started wielding his axe.
He was part of GE's team that worked with the OEM's on the PNGV program started by the Clinton administration - a 10 year program to develop an 80 mpg full size sedan.
He said that at the end of the program, the Big Three all submitted prototypes with the same basic powerplant -
A diesel-electric hybrid.
As far as battery pack replacement, imagine having to pay for a replacement pack outside of warranty. Let's just say it would make the cost of a new injection pump pale by comparison.
I know some gents in the EV community that bought Honda Insight hybrids when they first came out in 2000. The battery pack in those small beasts is nothing more than 120 NiMh D cell flashlight batteries, basically the same as what you can buy at Radio Shack, wired in series inside a sealed container with all the appropriate electronics.
2 or 3 years back some of the Insight owners were already past the 80K mile warranty on the battery pack, and reporting that the batteries were starting to get weak.
When they checked with their local Honda dealer about a replacement battery pack, being outside of warranty they were quoted $5500 plus labor.
Granted, that was for an entirely new drop-in battery pack ASSEMBLY, but still - that's for a relatively small battery pack using a commonly available battery cell size/design. What's it going to run for some of the more advanced hybrids using a one-off, unique, or proprietary battery cell design?
Not many people are going to have the money available, or be willing to put that much into a vehicle that already has 80K to 100K miles or better on it. They're going to dump it like a hot potato.
In this case, it looks like they may have achieved what I've heard many people for decades accuse the OEM's of trying to do - build a vehicle with a built-in finite lifetime where you have little choice but to buy a new one every 10 years/100K miles.