Hello Shekhar,
SAP IS Retail is recent module which has capabilities to integrate with various other applications for retail activities like BI (Business Intelligence) for Sales reports and monitoring and planning. It also includes SAP MM and SAP SD functions as well. If you have a good experience in retail field and you understand the business processes like from Vendor to consumer scenarios ( procurement to sales functions), then it will benefit you well. If you study SAP IS Retail from a recognized SAP Educational Partner , its fruitful as they will help you in getting a job where you get experience working on a project. Yes there is a huge competition out there because normally companies need 3-5 years experience in retail field with 1 or 2 end to end SAP implementation experience . So choosing an institute where you get trained you need to know about there placement process because if they don't help you getting a job in any company its very tough finding it for your own without the implementation experience.
About killing a Module is impossible. SAP always have the support for flexibility where the software is tailor made for a retail chain where the software gets implemented.
There are other SAP Modules like SAP BI/BW and HANA which are in demand as well. So it depends how well you Google and get to know what suits you for your career.
All the Best
Regards,
Jove