If those lithium-ion batteries are about as good as the batteries in laptops they should be good for about 300 to 500 cycles. After those 300 to 500 cycles laptop batteries are typically expected to retain between 80 and 70 percent of their charge.
That would be about 130,000km to 210,000km (assuming a linear decline in battery capacity – which might very well be wrong) with the 483km range battery.
That’s about 60km to 96km per day (and between 83km and 134km per day if the car is only used on weekdays, e.g. for commuting) if you want to get by with the battery for six years.
Lithium ion batteries, such as those in laptops, don't degrade based on charge/discharge cycles the way that older generations (NiCd, NiMH etc) did, but rather lose permanent capacity mostly as a function of time and temperature (although discharging below 20% or so exacerbates this).
If you have 2 battery packs you would still have a longer range at 70% charge than a single battery pack roadster. Still let's call it ~100k miles. Assuming 30mpg and premium gas (this is a sports car) your saving ~4$ every 30 miles by using electricity or ~13.3k. Drop that to 15MPG and your saving ~28k which is about what one pack cost.
That would be about 130,000km to 210,000km (assuming a linear decline in battery capacity – which might very well be wrong) with the 483km range battery.
That’s about 60km to 96km per day (and between 83km and 134km per day if the car is only used on weekdays, e.g. for commuting) if you want to get by with the battery for six years.