"Even if the tax credit is not killed off by the politicians (which The House of Representatives wants to do), it automatically starts to phase out once manufacturers sell 200,000 vehicles."
The real killer is going to be having competition. With other manufacturers releasing they own EVs, Tesla won't be the only fish in the pond and those companies won't have to buy carbon credits from Tesla either and that's been a healthy chunk of Tesla's revenue.
The real kicker is that Ford, GM and Chrysler can lose money on some of their EVs and the carbon credits they get in return allow them to sell more big phat SUVs with much higher profit margins so the bottom line improves. Gut Tesla's market for the Model 3 and that could kill them.