You mentioned the distance that has to be driven in order to trigger the environmental benefits. That number is no longer 80,000 kilometres; it is now 20,000 or 30,000 kilometres thanks to improvements in the manufacturing of electric vehicles.
As for the lifespan of an electric vehicle versus a gas-powered vehicle, I would have to say it depends on the make. It's the same for gas-powered vehicles: some last longer than others. An electric vehicle can travel up to 250,000, 300,000 or 500,000 kilometres. Some gas-powered vehicles can last a long time as well.