Unlike Kilo, where only 2 out of 6 tubes can fire LACMs, in Scorpene, all 6 can fire MdCN. And it can very well carry 18 MdCN or a mix of 12 MdCN and 6 F21 torpedoes.
That's pointless. Can't carry one for the other. The primary duty of the Scorpene is to hunt and kill submarines and ships, land attack is a secondary capability, and most of it is needed for the anti-ship role using the Exocet now and Brahmos-M later.
Also, torpedo tubes primarily are equipped with torpedoes rather than land attack cruise missiles because reequipping them can either be impossible or time consuming. So you can always expect most or all torpedo tubes to come with torpedoes. Only 2 torpedo tubes are sometimes equipped with AShM, sometimes none. Allowing all 6 tubes to fire missiles is only for the sake of flexibility.
The next line of subs will carry land attack missiles in VLS, and only those missiles are generally used for land attack, while maintaining the torpedo based missiles for anti-ship role. Although, with Brahmos, you can use it for both.
As for further Scorpene orders, from the time a new contract is signed to the time the first sub is delivered, it will take 7+ years. This is about the same time it will take for new gen subs to start coming in. So it makes sense to end Scorpene with 6.
Brahmos is a costly system, if need arises to say attack Quetta Airbase from Arabian sea, it would be better to use 20-30 Klubs, not 20-30 Brahmos, they are costly and would be used for specific targets only as we cannot have them in very large numbers, but we can have something like Klub or MdCN in thousands , Navy wants something like 1000-1500km range subsonic Klub but with better terminal guidance to increase accuracy. The French and British SSNs fire LACMs from torpedo tubes, so no problem for IN to use Scorpene for the same purpose.
It will only reduce complications.
Klub has to be fully imported, more than half of Brahmos is now made in India. It's obvious we will use Brahmos. For long range, we will use the new long range missile being developed in place of Nirbhay. I don't believe there are any plans to buy the long range version of Klub as of now for use in submarines. Even the MdCN will not be required. Our long range missile will come with anti-shipping capability as well.
