Hi, As per your concern, check the scope for all below:

Thermal : Thermal engineers maintain centers for electric motors, pump sets, oil engines and other manufacturing equipments. Some job titles are - Lecturer Researcher

Plant Chemist

Piping Designer Trainee

Maintenance Engineer

Field Service Engineer

Design: With this you open up options like in aerospace, automobiles, bio-mechanics, micro mechanic etc. It also has wide scope in research and development.

Manufacturing : Some of the fields you can go in are Plant Engineering, Process Engineering, Quality Engineering, Industrial Managers and Operations Analyst.

CAD : Scope is good and broad  in it.

Also its not the scope that matters, but your interest and passion.

Decide wisely.

Good Luck.