There's a fair argument that the volt is a better economical buy than the used leaf.
If you need a commuter car to get you to and from work every day, and errands/visiting people in town on the weekends, getting one with a fuel cost per mile of 15% of normal (or even free if your work offers charging) makes a lot of sense. The 90 mile range is rarely a limitation at all.
If you need a car for frequent long trips out of town, the 90 mile range would be a huge hindrance. In that case I would discourage you from buying a 2015 Leaf.
But if we're being honest the money you lose after a decade is a lot less then the money you saved when you purchased it.
In fact, they specifically poached a number of former executives from BMW's M division to lead those projects.
But when it comes to warranty you should take care, people imagine this is like the warranty on their phone. It's not, basically it says the body won't rust. The rest is covered by dozens of other clauses that more or less just guarantee than almost nothing gets replaced under warranty.
Furthermore, almost 80% of electric cars are leased [1]. When electric cars aren't being made for compliance reasons, or to lower the overall emissions of an auto maker's fleet (and thus subsidized in some way), then resale value will be of critical importance.
[1] https://www.bloomberg.com/news/articles/2018-01-03/why-most-...
Mercedes & Tesla trade at the higher end, where just the impact on perceived quality (in addition to the quantifiable financial benefits of buying a car that will maintain value) is important. OTOH, EV are already knowingly buying a car that ranks poorly on that front. Who wants to buy a 2015 model EV in 2018? Range improvements alone would kill the price.
So... not sure it matters too much yet. Going forward.. who knows. I think tesla may already be "in for a penny, in for a pound."