1. Tesla Model S 85D hits 300,000 Miles with less than USD11 000 maintenance costs - They compare this to a Mercedes S Class having $86 000 in maintenance costs and they hope to drive this car for another 900 000kms.
2. Martin Steinbuch posted a blog post about Model S battery degradation data taken from this publicly shared Google Sheets data. The data points to a 1% degradation for every 50 000km travelled with a lifetime  (still 80% capacity left) of 840 000km.

Even taking my confirmation bias into consideration, that's an impressive long lifespan for a car. With my average of 20 000km - 25 000km driving per year, that's a lot of years. 

Edit: minor spelling mistakes