Hi, thanks for your point of view. It is good to debate positively. Let me contradict u on ur points.
1. As u say air fares wud increase from 1500 to 4500 over next few years. This may be true or may not be true. Because if u check the past, flying was unaffordable with high fares. With each passing day, air travel is getting more and more affordable.
2. Bullets trains wud not be used by those cost conscious passengers who prefer to travel by SL class today. They would still...
more... prefer normal trains. Bullet train passengers wud be used by those who prefer to travel on Shatabdi, and upper AC classes. Business people will more and more prefer airlines as time passes.
3. If air fares are subject to exponential increase, we wont have 1500 fares today between mumbai and ahmedabad as it is seen today.
4. This is not about airlines replacing the railways. This is about spending lakhs of crores on something which won't be used by the masses. Instead, railways should use the money to improve and upgrade the existing railway infrastructure which is creaking at best!
5. Yes, Bullet train is undesirable because Indian railways is always short of funds for quite important peojects like giving rail connectivity to areas with no rail connectivity at present. Mumbai and Ahmedabad are already well connected by rail, road and air. So spending a huge amount on an already strong sector which has ample capacity is injustice to those that don't even have rail connectivity!
To conclude, in my humble opinion, Railways shud use precious financial resources efficiently n smartly instead of putting into something for mere show off to show that India can have bullet trains!