the one area where there is likely to be most improvement is time needed to recharge. right now you basically have to charge it overnight but someday in the future you might be able to recharge your car while eating your burger at Wendy's
but ultimately the success of electric vehicles hinges on the same issue as success of ethanol does - there needs to be a distribution network for the fuel / power.
before electric cars take off all manufacturers of electric vehicles will have to agree on a standard charing station design. then they will need to invest HUGE amounts of money to actually put those stations in places where people can use them. until these two things happen electric vehicles will essentially be useless for anything but a second or third car.