Placement for quantitative serving at NICMAR is good. A lot of people get an average package of 6 lakh per annum even though they are fresher. According to the recent placement highlights the highest CTC offered at the institute was 12 LPA. Hence, it is worth it. So, you can definitely choose the course if you want to do quantity serving for most of your career.
Considering all the growth in the infrastructure sector of India, there is a good scope for it and it will go on like this for the next 5-6 years.
QS has been a favorite for almost all the fresh graduates. As it has a better ROI as compared to a full-time two-year course. You should not opt for it as a career just because you like the subject in your engineering syllabus.
It would be better for you to get on a job on-site first. You can work for a year or two and understand the activities that go on around. During this period, you will also understand if you can do a full-time QS job. And then if you are still interested, you can go for it. QS has an unlimited scope with several growing projects in India and abroad so you need not worry about that.