Hello!Anurag

Yes,you will get top 10 NITs with 187 marks under general category but chance of getting core stream is less.With HS quota you can secure seats in core stream.187 is descent marks in JEE MAINS,these marks will provide you lot of NITs with core and non core stream.Right now, nothing can be said about cuttoff and rank in EWS category.For sureity wait till NTA announce rank for each category.

Ask for any query.

GOOD LUCK!