@PARIKRAMA thanks for the tag.
Well yes I sense a change in plan for P75I and that is what a delay is about.
Despite the news that announcements will be soon, it will take time. The P75I will be the most advanced SSK patrolling the oceans and most costly too, so they will take their own time. Meanwhile addition Scorpenes, Kilos and Akulas will keep our fleet going at minimum operational level ( if these are at time, then it will take us to our minimum desired levels , where our Submarines resume long patrols far away from our shores , at present Kilos are not sent for long patrols , after an upgrade they will resume it. )
You forgot the per capita basis argument vis-a-vis Pakistan.
Turkey has the same number of 13 boats as India does (leaving the leased Indian asset). Now where is Turkey and where is India?
Per capita assets is not often an ideal situation in Naval operations. And as for Turkey or SK or Japan, each nation , I repeat each nation has its own objectives and own operatinal needs to be fulfilled.
There is a reason why Navy is the most distinct out of 3 arms .
As in case of India,
Is India in lack of submarines ? => Yes
Is India behind its minimum operational needs ? => No.
Well India does not need to conduct the same level of Submarine operations in Bay of Bengal as it needs to do in the Arabian sea.
That should help your questions.
As for Australia & Collin class. Who is Australian adversary/enemy?
Again ignorance.
If you check out the Submarine operations in strategic South China Sea of last decade, you will find out its the Collins Class , its the only main diesel SSK opponent of PLAN in SCS,so much that China has its Spy Satellites positioned to carry out surveillance of Western Australia Submarine base, not of Japan, not of SK, not of Vietnam but of Australia, that should get you to the answer .