And then there's the fact that the people who can afford a new electric vehicle are already driving newer, well-maintained, low-pollution vehicles anyway. The old, unmaintained, clunkers, driven by people who can't just run to the dealership and buy a new car on a whim, will continue to be driven and continue to pollute for a long time to come.
You're contradicting yourself here. By having the wealthy go out and buy clean very-low pollution vehicles, they end up selling their well-maintained low- pollution vehicle to the less wealthy person. In the end - a dirty clunker will end up off the road (or at least driven less).
Add in the severe range limitations of electric vehicles, and the lack of progress on addressing that issue, and I think 10 years is FAR too short of a time frame to bet on electric vehicles becoming mainstream. Plug-in hybrids? Maybe. Pure electric? Zero chance.
I own an EV and I agree that EVs will continue to remain a small part of the market for the next 10 years, but I guess one has to know what your definition of "mainstream" is. PHEVs will definitely sell in higher numbers for the time-being - people simply aren't used to limited range and quick-charge infrastructure is still very limited. I do think that once the mainstream EVs get up over 100 mi real-world freeway range it will eliminate a lot of the range anxiety for the vast majority of daily driving and sales will increase significantly.
As for the the lack of progress on addressing range? I'd argue that there is definite progress being made. The Tesla Model S is being delivered today with a real-world range of well over 200 miles - comparable to many gas cars (yes, many gas cars can also go 400-500 mi/tank).
Another example of progress? The PHEV Volt has improved EV range from 35-38 miles since it's introduction - a small increase perhaps, but 8% is definitely evidence of progress.
If you want a practical, low-pollution alternative, the best bet would be a plug-in hybrid that burns propane in the internal combustion engine. Much cleaner than gasoline/diesel, and I can swap an empty 20# propane tank for a full one in any populated area nationwide.
Not a bad idea, but still 20 lbs of propane is the energy equivalent of about 3.4 gallons of gasoline. I guess if you could build a propane ICE as efficient as a Prius (50 mpg) that would be sufficient, that'd be OK if your goal is longer range transportation.
Certainly as a range extender for a mainstream EV it'd be sufficient for the vast majority of use. For longer trips just go rent a hybrid.