Without the advent of the lithium ion battery, we wouldn't even be having this conversation, since lead acid wouldn't get the range without adding immense weight. I suspect battery technology will continue to improve and getting a viable all electric vehicle (1000+ mile range) is probably not too far in the future. Even then, there is the problem with charging. That is still going to take time. You can't pull into a station, plug in for 2 minutes and expect to have a full charge like you can when you fill up with fuel. Hybrids mitigate this problem, but that also inserts additional weak points and maintenance issues for the owner.
My biggest issue is that people seem to think that electric vehicles are somehow "green" and don't harm the environment when the fact is that the energy that charges the batteries largely comes from coal, natural gas and nuclear power. All of which have their environmental impacts. For that matter, while hydroelectric, solar and wind are much more environmental friendly, they still have a certain effect. What happens when all of these batteries have served their useful life? Imagine for a moment, that all of the cars on our roads right now were electric. Think of the environmental nightmare dealing with the huge amount of used batteries that would accompany that. If you've ever seen a lead acid battery recycling facility, you know what I'm talking about. Lithium ion is no doubt even more hazardous and hard to deal with.
If Elon Musk wants to really do something, he should be putting his efforts towards hydrogen and finding a method that's more cost effective to produce it in volume and make it as safe as possible for a passenger vehicle. The hydrogen fuel cell is by far the best option for the future of automobiles, IMO.