Ofc it will be possible, just like currently people trade illegal goods on the Internet, except it's even easier, because Bitcoin is not physical, so there's no problem with delivery, although it still can be found, because there are seeds, flash sticks with wallet files, hardware wallets, ASIC's and so on. But the question is how many people will be deterred by the ban, and how far India will go to enforce this ban - if they will be really harsh with it and actually throw hundreds or thousands people in jail, than Indian crypto community will be significantly reduced.