> The battery in the BMW i3 has held up fairly well.
This is likely because the car limited usage to between 20% and 80% of actual capacity. I verified this by looking at the raw data.
In comparison my new Renault Megane E-tech has 0-100% available. You can limit daily charging to say 80%, but the manual states that if the range goes below 15km the car may shut off at any moment.
On a different note, not all cars have easily replaceable batteries. So labor cost might be quite high, in addition to the new battery. The i3 was decent and I saw someone doing a swap for about the same total cost as replacing an automatic transmission say.
Not sure how my current car will fare, I certainly haven't planned on replacing it after the 8 year warranty expires...