3 submarines have been launched - Kalvari, Khanderi, Karanj. Other 3 are in constructions at various stages.What are you saying about 2025? By 2021 all the 6 submarines would have been delivered and before 2020 itself an assembly line will get empty and will have to get new orders to maintain skilled workers. So, the next 6 submarines will also be completed by 2025 if the pace of construction is increased a little.
About Arihant class submarine, it was always meant to be SSN, not SSBN. It was simply stated to be SSBN to divert attention. Realistically, there is no point in having SSBN except to target USA or other American countries. All other countries are targettable in Agni-5. The concept of second strike is foolish at best and there is no way anyone can take out the nuclear missiles kept in safe locations like under mountains, lakes etc as hardened silos. India can easily keep some hardened silos under western ghats or Himalayas or under big lakes like Chilika lakes etc. Also, the radars give early warning about missile launch and hence there can be no surprise attack either. Also, Indian Arihant is the same size of Akula and is a small submarine to be called a SSBN. No submarine that is intended to launch ballistic missile is that small.
Scorpene will be eventually indigenised 100% and will be made in India with some design alteration to avoid sensitive data from being detected by France