That is the issue that I was highlighting. India was sitting on the offer from 2012 and did nothing until China close the deal in Nov-2014 ahead of India. In spite of the pressure that started to build on GoI, it still took 3.5 years for GoI to close the deal. That is a pathetic performance. GoI cannot hide behind the excuse that there was no money. All they needed was some money to make the advance down payment as the systems would have only been inducted in 2018/2019 right after the deliveries to China have been completed.
The IAF was probably waiting for the conclusion of the MMRCA instead.
Didn't people claim that S-400 was getting delayed as Indian deal would include S-500 tech unlike the Chinese deal?
Of course IN would be the first line of defense but India should plan multi-layer defense. There is no guarantee that the naval defenses won't be breached.
I don't know to what extent we will have S-500 tech. But we likely have a production deal because they were discussing about ToT and stuff.