On what basis, you come to conclusion that the requirements where given much before? I have not came across such news, if you have please point it out. Sorry but unable to understand "platform firing version", what exactly you mean?
First of all, the "final validation trials" where done in which the capability for hit the stationary and moving targets where established, also the namicas have proven there capability to cross the water channels. As of now it has one sight, now two sights getting demanded which will definitely require the redesign. Was IA sleeping till this time? Why it is so problematic to start inducting it and seek batch wise improvements?
The article says,
"Two systems would be made — one by Bharath Electronics Limited (BEL) and the other by Larsen & Toubro."
This means contracts have already been signed. Thus requirements would have existed even 6 months from now. Contract signing takes minimum 2 months because of the scope of the project.
Platform firing weapons means Nag being fired from the BMP-II or the LCH, where BMP-II or LCH is the platform and Nag is the weapon. It simply means Nag is not hand held.
The final validation trials have not taken place. This is what the article has to say,
" the sources said adding the DRDO proposed to carry out a guided flight test against a tank target by the end of the year,"
This means Nag has not even been used on a tank until now. They were all used on dummy targets. Nag tests are meant to end only in 2011-12. This means the new platform will be ready the same time as Nag.