I don't get it. You don't need to use the hawala system to send money. There are a gazillion different ways to send INR to USD - PayPal, Western Union, Moneygram, SWIFT etc. etc. Each time, you have to pay fees, taxes, etc, but each time you still make a handsome 25% profit.
The hawala system is mostly for black money, laundering, tax evasion etc.
I'm going to be in India in December and probably could report how it's working than ;)
So far I've checked on LocalBitcoin, if I want to sell BTC the price range is something like 800-920$ ( and about 1000$ if I want to buy )
But the only available mode of payment for BTC seller is "transfer to account in Indian Bank" ( no credit card or Western Union options provided, also you can buy BTC with Western Union ) Also as far as I know it's possible to get an account in Indian Bank even with tourists visa ( you have to provide a rental contract) but probably due to this notes shortage the money would be to hard to withdraw.
India has capital controls. You can send money to India freely, but you are limited as to how much money you can take out of India.
Also, they reckon that half of all money in circulation is black money, so sending it via official channels will get get you caught and fined. If taxes + fines are greater than the hawala fee, then it's cheaper to go hawala.