Umm, no.
I'm Canadian and I understand US tax credits better. From what I've seen, its full credits (to the extent of individual tax circumstances) on the first 200,000 cars SOLD in the USA (not worldwide production/sales) After that, it ramps downwards much like the situation in Denmark in 2016 with a 20% reduction compared to Denmark's full credits in 2015 and before, then another 20% further downwards in 2017 etc until the exemption is gone.
The US credit is by qualifying vehicle, even if that said vehicle only qualifies for a partial credit as in a PHEV like a Volt or a Prius Plug-in, and since it is by car and NOT divisible, GM and Toyota and Ford have been blowing their entitlements to owners getting tax credits on cars like PHEVs that only qualify for smaller tax credits.
So, last year Tesla sold 50,xxx cars worldwide, but only 26,xxx ? cars in the USA, so there is a long way to go before the tax credits run out. Years. Total tax credits for Tesla including Roadster, S and X are likely about 50K total sold in the USA, so still 150,000 or so sales **in the USA** to go, before they start tapering. Remember, for every Tesla sold in the USA, at least another will be sold elsewhere, so if 100,000 Tesla are sold in 2016, that means about 50,000 in the USA, so still 100,000 US sales with full tax credit to come. That should take Tesla well into 2018-2019 and the launch of Model 3, and Model 3 variations.