The internal combustion engine isn't in its death throes yet, but it will be soon. The Volt was proof of concept, and the Tesla 3 will convince the masses to make the shift. Already Volvo has announced that they will develop no more ICE's and GB has announced it wants to be all electric by 2040.
The $7500 appears to still be in place unless something has happened this week, and many states have additional rebates. In a couple years, those rebates will no longer be required in order for pricing to be competitive. Already you can get a basic Tesla 3 for $35k. The big step up is to increase range from 220 miles to 310 miles. That is an additional $9k. Don't want it? Don't buy it. But most folks who are looking at 3's don't really care about an additional $9k.
At the other end is the Nissan Leaf. We are probably going to get one of those soon, used, unless we hold out for a 3 or a Renault Zoe. 90% of our driving is back and forth to work, 12 miles each way. We can charge at night when the rates are low. Gas here costs $7 a gallon. We currently drive our RAV4 to work and back, getting 20 miles to the gallon. Shifting to the Leaf would save us over $2000 a year. We can buy a late model leaf down here for about $22k. Looking at Mitsubishi PHEV SUV for a new "big car" to go with it.
Lithium isn't really an availability problem.
Here is what I think will ultimately cause headaches for consumers and delight for the car industry down the road: cars will become like laptops. Nobody will want one that is three years old, because the technology in the new ones will be so much better. I'm looking at a Leaf right now. There are two generations. Lord knows I don't want the old generation even though it works fine. And then there is the 3 and the Zoe. Much cooler. And so on....
It will all be interesting, but faster than we think, it'll all be electric.