I think if India does as you say, the type of timeframe in which...

I think if India does as you say, the type of timeframe in which it is likely to occur, and the likelihood of the demand becoming sufficiently high as to make low grade isolated magnetite deposits lucrative (the China boom didn't do it) would likely mean by then the bird droppings will have truly petrified and the potential for a phosphorous play will be a realistic option.
With the abundance of high grade hematite readily available they may have to wait a decade or two.
Dunno if the supply of birdseed will last that long.
Can't see the supply of bull droppings lasting that long either.