It is tough to predict.
Given that the world is moving in a specialist direction, this can very well happen. That being said, the IAS lobby is pretty strong and at the moment the kind of relation that they enjoy with the political class is almost unparalleled. This is not going to change anytime soon, because they keep running into each other because of the developmental nature of their job.
However, two things can be said with fair certainty. One, at the moment, IAS is the only service that stands to lose something while all other civil services stand to gain from what IAS will lose. And the process has already started12.
Two, at present, IAS is the best first option when you consider overall probability for career growth. However, no body can say that this will be the case for all time. You can only make educated guesses. There was a time when IFS was the best first option ( when Nehru was the Prime Minister), when IPS was the best first option ( during Indira Gandhi’s time) and many say with the Indian Economy about to become the world’s economic pole, the time might as well have come for the IRS.
You can never tell.