But what about calendar life?.... deep cycle lead optimized for storage like the kind sold for off grid solar can last 5-10 years or more... but LiIon seems to loose capacity with age a lot faster and even treated gentle most of the commercial batteries ive seen struggle to last longer than 2-3 years.
I didn't find good data on that, but as woodgeek noted, they seem to have gotten pretty good in recent years, with some offering 10 year warranties.
Keep in mind also that there are several different types of lithium ion batteries which tend to trade off capacity or amp ratings for reliability. A lithium-iron phosphate battery in a car might get 10 years no problem, while a lithium-manganese oxide cell phone battery struggle to get 2 years. However, while there are real life span differences between the various lithium ion chemistries, note also that a big part of that is also the different usage (which again, woodgeek also alluded to). A smart phone battery will probably be almost fully cycled daily - 700+ times in that 2 years, while a Nissan Leaf battery would likely get half cycled 2000+ times in its 10 years.
As far as $200/kWh prices - I've seen that figure tossed around, but it's not clear to me that you can actually buy a lithium ion battery for that price at the moment. Apparently it comes from Tesla saying replacement batteries for the Model S would be $17,000, which for an 85 kWh battery, is $200/kWh, but that doesn't mean it's what it cost them to make batteries now. Elsewhere, I've seen the figure as a cost target for when Tesla's battery factory is up and running which makes sense.
A recent study indicated current prices for the market leaders are more like $300/kWh, and for lower volume users, more like $400-500/kWh. The Powerwall is priced $428/kWh.
Regardless of the battery tech in question, the battery isn't the only cost, as there's also installation and power conversion (for a home, an inverter) to consider. At the utility scale, the pricing gets more hazy because they have better economy of scale, but have to integrate with a much more complex grid. I'm loathe to use this example, but since I have the numbers handy - my own utility just installed a "large" (for this sort of project) grid storage battery system with a capacity of 7400 kWh for $16 million - that's $2160/kWh.
I'm loathe to use the example because that price appears to have been artificially inflated by corruption - It recently came out that the company hired to do the installation is owned by a personal friend of the PUD executive. He was previously hired on to the PUD by that executive into a special position created for him and wrote their specification for a grid storage system, then left the PUD to start the company as a reseller of other companies' batteries and was very shortly afterward awarded a contract without a competitive bid for the spec he wrote. That's not even the entirety of the shady details. Somehow, all that's happened so far, however, is the PUD hired an "independent" lawyer to investigate whether there were any "inappropriate activities" at the PUD, who unsurprisingly released a report than concluded the agency paying her fee was innocent.