In US, a lot of channels are still broadcasting 4:3 even though a very small number of people have 4:3 TV sets. I am sure the number is very high in India of those households having 4:3 TV sets.
One option is to put "16:9 shrink to 4:3" option in STBs and sell those STBs to 4:3 households.
"4:3 stretch to 16:9" option is available on many HD STBs.