Good solid points, Bob, and I think probably the answers are multi-faceted?
Firstly, I would think a forward-thinking and enlightened government (and, no, I don't know where we're going to find one of those either) would have been buying EVs exclusively for its own fleet and obliging Local Bodies to do the same - starting about five years ago - we would already be enjoying he benefits of the three-year-rollover of vehicles into the national second-hand fleet/pool if that were the case. I think we are considering these moves now-ish . . . so in another few years . . .
Batteries? I think the conventional wisdom is about 12 years life (with substantially reduced range for the last couple of these) BUT we are already seeing market forces at work as aftermarket players begin to supply battery packs for the Nissan Leaf - and I guess others will follow. Costs might be in the order of $4K landed as opposed to estimates of $7-12K as OE parts
On that basis, with a "fuel" cost around $0.02 a kilometre and "maintenance" around $0.01 a kilometre (depending on who you believe) buying a, say, $20K car as a five or ten-year proposition makes a lot of sense
IMHO it will be interesting to watch as market forces do unexpected things in this area, and as petrol costs and taxes change over time, and as tech advances change the market too
Cheers