L&T is not idle. They have received orders for 3 CTS and 2 MPVs.Pipapav couldn't execute its maiden naval contract for 6-7 NOPVs because of Chota Ambani's cash crunch. This experience would have surely dented the IN's perception about the capability of private yards to deliver on naval requirements. AFAIK all big-ticket orders since have gone to PSU yards who smartly subcontracted work to idling private yards like L&T!
Among private shipbuilders, I believe only L&T has developed some credibility by delivering the ICG Vikram class ahead of schedule. Their contribution to the strategic sub programme will also stand them in good stead.
Things could interesting though if Adani or even Mukesh Ambani entered the military shipbuilding business.