It will not have that huge impact as the news there is emphasizing. People will be more careful and will have more RS 50 rather than few RS 500. It will not be any problem for the black markets as they will find a way on how to deal with each other, they can do transaction in a car for example, they simply cannot be stopped. The true motive behind such move is to exert more power over the people.
I even checked how big is a RS 500 compared to RS 50 and I think it will be no problem for people to keep more RS 50 with them rather than a RS 500. So this move will not affect anything in terms of economics as far as I know from this field.
corruption and illegal currency is the biggest problem in india,the ban of rs 500 and rs 1000 all of a sudden is a big surprise and from tomorrow onwards those who are having the said currencies will not have any value and cannot exchange through stores ,the only way to exchange is through banks,since this news is announced in such a short notice it will be difficult for people having large amount of currencies stached inside their home to exchange it .