The article doesn't mention this for some reason, but the iPhone 6 (32 GB model, which didn't previously exist) has been manufactured in India for a while now in order to sell it in India as well as some other countries (including Western countries) exclusively through carriers as a low cost alternative to the iPhone SE. I suspect that these assembly lines are finally being switched over from making the iPhone 6 to making the iPhone 6s.
Pretty certain the iPhone 6 has never been assembled in India. The 32GB iPhone 6 has been re-launched in India and other price sensitive markets, but it's assembled in China.
The SE is the only iPhone assembled outside of China. Now, that includes the 6s.