Electric cars are a niche application
"How long before electric vehicles wipe out the internal combustion engine?"
Why would they? If ample, cheap electricity is available, it would make a lot more sense to synthesize pure (sulfur-free) hydrocarbons out of atmospheric CO2 and water, and use them to fuel IC vehicles. Since we'd be taking as much CO2 out of the atmosphere as putting back in, the only greenhouse-gas contribution would be water vapor. And transportation's contribution to greenhouse gasses already isn't all that large - take out extracting, refining, and burning natural fossil fuel and it's negligible.
Electric vehicles are a lousy idea for most applications. They require lots of high-density batteries, which means mining lithium (wasteful and destructive), manufacturing batteries, recycling batteries at the end of their short lives, and hauling a bunch of weight around. They have lousy range and long refuel cycles.
Internal combustion engines have great power density, and we already have a lot of them, plus a whole infrastructure for distributing the fuel and refueling vehicles. Fuel is easy to store and transport.
Hell, with some improvements in fuel cell technology, it'd probably make more sense to build an electric car (if you absolutely must have one) using fuel cells and synthesized pure hydrocarbons than with lithium-based batteries. Or just a good old diesel-electric design.