It's possible. India certainly has a wealthy class, but whether they start spending big money on english language .in domains is yet to be seen.
As far as when a huge sale might happen, there's absolutely no way to predict that. Domains aren't like commodity products where the market has fixed parameters. In order for a million dollar sale to happen, two things must first occur.
1) Someone very wealthy must want a particular domain name very badly and be willing to spend $1,000,000 to acquire it
2) Whoever owns that domain must be a VERY unmotivated seller and have the courage to turn down huge offers and risk breaking the sale, in the hopes that the seller is willing to go a lot higher.
As someone who's negotiated a few decent domain sales myself, the one thing that is always in the back of your mind is that in order for a domain to sell at $1,000,000, the owner usually must first turn down offers of $100,000 or $500,000 or $750,000... Of course, as someone who's LOST a few very lucrative offers- that I wish I had taken- due to greed and overestimating the financial strength of my negotiating counter-party, turning down huge offers in the hopes of an even bigger offer is a lot easier said than done.
It's going to be VERY hard for most people involved in the .in namespace to turn down the types of offers that precede a $1,000,000 sale. If a $1mm domain sale does happen in the .in namespace, it will probably be between two major Indian businesses, since that's the only way I can see a .in name scaling to those heights before the seller can't justify turning down the cash.