Value of money after 25 years !!?

i am 30 yrs old. I am planning to invest 70k in PPF every year and after 25 years it will come around 50 Lakhs. I want to know if there will be any value for 50 lakhs 25 years down the line. Other than tax benefit does PPF really gives us social security with such money after a very long time. %0 lakhs looks a big amount now, but after 25yrs, i am just confused. WIll it have a value.

Kindly place ur advice and suggestions. Does Public provident fund(PPF) make a good investment decision or is it just a tax saver with no useful value money when u get it back after 25yrs.