I wrote a blog post to help put Tesla's position in perspective.
https://carswithplugs.wordpress.com/2017/12/13/2017-li-ion-ev-fleet-capacity-usa/
Tesla is always getting ahead of themselves. If you don't try and fail you are probably not doing anything. They have done fairly well considering.
People really need to stop underestimating Tesla. The market and perception of buyers is shifting to BEV, and Tesla accommodates that with superchargers and long ranges. My personal thought is the batteries would be better suited to PHEVs initially, as you can make 5 to 10x for a single Tesla battery and likely offset more gas miles, but I know this won't be popular opinion.
I think Tesla's semi will be able to show real cost savings for truck fleet owners, and emissions offsets will be massive in city stop-go-idle applications. I am also confident Tesla has the potential to be the largest car company in maybe 10 to 20 years. Clearly, things will shift as other companies react more (they already are), and depending how much Tesla stumbles