According to the Toyota site a Prius is $24,000-$29,805 base MSRP, depending on which version you get. I don't know which one is most comparable to the features on the Volt, but it's probably not the cheapest one.
They also compare it to the all electric Leaf, and the all gas Chevy Cruze.
They list the per-mile costs of those, but they don't do a direct comparison on the time to break even on the difference in price between a HEV and BEV. I don't see an analysis of whether a (mostly) BEV is worth the extra cost over a HEV on the wikipedia page nor the pages it links to.
The battery probably will last longer than the warranty period, but did you read where Chevy estimates that it's capacity will be reduced 10%-30% in those 100k miles? Oh, BTW, that's 100k vehicle miles, not 100k electric miles. By the time you hit 100k-150k electric miles, the battery is expected to need replacement, if for no other reason than significant loss of capacity.
That's not a thorough analysis of the mean lifetime a buyer can expect for a battery given any replacements they might get during the warranty period. It only makes sense to buy a Volt if the vast majority of the miles will be electric, so it makes sense to assume most of the miles will be on electric. If you frequently need a longer range, you are probably better off with a car that has a longer range at high efficiency.
The Edmunds analysis you cited says that the payback period is 135K miles at $5/gal which is within the expected lifetime of most cars, and it seems to be around 90-100K miles for the more common HEVs (the full-electric leaf is at the low end of the range). But number of years to break even on a price premium is not the same thing as total cost of ownership- what you really want is the total discounted purchase, fuel and maintenance costs over a given number of years/miles, minus the residual value at the end of that period. And yes, you might have to replace the battery (or maybe it'll get replaced under warranty). You also might have to replace parts on other cars.
So if you only care about total cost to yourself (it's beyond me why anyone thinks buying a car is a good way to save money), and you will generally drive within the electric range, and you expect gas prices to rise significantly relative to electricity prices, then your total cost of ownership will almost certainly be lower with a Volt than with a regular gas car, some HEVs would probably "save" you more, and a full-electric (if the range works for you) is probably the best deal. If gas prices stay the same, you'll probably have similar total cost of ownership either way. Not owning a car at all will save you more.
These arguments that electric vs gasoline cars are a bad investment remind me of the exact same argument a few years ago about how hybrids, and now people like you are insisting on comparing electric cars to hybrids to decide if they're "worth it." Lots of people buy SUVs. How long do those take to recover their price premium?