There are many reasons for it and important ones are:-
1. It is the most ancient existing practicing religion without a broken chain.
2. Its philosophy is the most comprehensive and encompasses all the possible aspects later adopted by the other religions.
3. It is the only religion that has material and medical science also the part of religion like Ayurveda.
4. Its the only religion that has in detail covered the science of deeds (karma) and its management and is often refereed as Karma Yoga.
5. This religion is based on the basic truths of the universe and therefore never ceased to exist.
6. The only religion where the philosophy and its practice are so well meshed that it became a way of life.
7. It will ultimately lead the world to Peace and away from the chaos.
8. It was the understanding of this religion that Mahatma Gandhi without resorting to any violence made the violent Britishers leave India the jewel in the crown of British empire.
9. Its basic philosophies are summarized in Bhagwat Gita.
10. You can practice Hinduism but to be a Hindu you have to be born a Hindu. Conversion to Hindu is not permitted unlike other religions who are using all means to convert people to their religions and leading to violence including Jihadis.
Yes, millions in India and all over the world.
yes
Hinduism is still practiced today, it dates back to about 1750 BCE.
The decendants of the incas still do exist today.
The incas don't exist today
Yes it does exist today, but it did not exist until the 1920's.
yes iis still exist
Slavery did exist in 2004 and still exists today.
Olympia, Greece does not exist today.
No it does not
does the caddo tribe still exist today
Yes and it still has a lot of Hindu people today.
Yes famine still exist in many parts of the world.
It is a foolish question, first of all. There is no end for Hinduism, till this world exist.