Eventually you are correct, we will move into full AC trains including gen coaches. Also purely from a stability , equilibrium perspective, having sleeper and general compartments which have windows on either sides and winds and dust blowing from both sides may not be ideal to run high speed trains. However, railways could have done these things in a gradual phase manner. What has it resulted in ? The lower income group who have reserved tickets are made to travel in coaches which is full of unauthorized passengers. Comfort for this category of passengers has been given low priority