Hey Shalini,
I'll briefly respond to your queries:
1. From commercial and industry usage point of view, the current state of Big data technologies is that it has proven its worth in a lot of scenario's and has potential to solve many more other challenges. You can find the amazing stats supporting the same in numerous places all over the internet. If you are looking for more than just stats, then please go through the course
Big data and Hadoop essentials and it will explain its huge potential in a brief manner.
2. There are two ways to look at it. 1. Technical 2. Commercial. Technically, hadoop is a distributed computing framework. So alternatives to distributed computation framework are HPC, Grid Computing and Volunteering computing etc., but the beauty Hadoop is its ability to use the commodity hardware to yield performance that is scalable. To understand about this in little more depth you would have to go through the course for
Hadoop Certification) That is why from commercial point of view, it has no alternatives yet to the general industry Big Data problems. Other solutions like Grid Computation, Volunteering Computations have only specific use cases. Hadoop is more general and can address far more issue in far more better manner.
Hope this helps! Do let me know if you were looking for something in specific!
Best,
Nitesh