Dear Aspirant,the mechanical engineering has vast scope in every field. They have plethora of opportunities in aerospace, chemical manufacturing plants, automobiles, railway coach factory, oil industries, reasearch and development etc. Apart from this, they have wide opportunities in PwD as well. So mechanical has high scope in near future. IIT Delhi offers average package of 9LPA. Highest package was of 45LPA. This keeps varying every year. So yes it can increase after 4 years.

Hope this helps.