In light of the new scheme of things, what opportunities do Economics graduates have 2017 onward with respect to the service groups? PAS, PSP and FSP still a possibility? Or are there only service-specific tests for ALL graduates regardless of degree majors?

Very little time is remaining (Just over a year) for 2017 aspirants, yet the policies aren't announced yet. For people who are devoting all of their time to preparation for the CE, it may be enough remaining time, but for persons working full-time, it will be a real challenge to prepare thoroughly for CE-17 if the policies are announced deep into next year.

What will be the cluster based system? What subjects will one have to study to compete for specific groups? I hope the policy of subjects, qualification, age etc. are released soon so everyone can begin focusing on preparation.

If I were to guess the subjects for PAS they would be Town planning, Public Administration, Political Science.

FSP cluster might be Islamic History, British/US History, International Relations

PSP cluster might probably be International Law, Constitutional Law, Muslim Law, and General Law

I guess you might be compelled to select the above subjects along with other subjects like Gender Studies, Computer Science etc if you want to join the above three groups.

I wouldn't take this cluster based implementation too seriously.

For e.g, if someone has scored 180 in accounting and ranked in the top 10, he'll only be allowed in the Audit/Accounts group?

Impossible!

I think simple Master degree would be the requirement rather than Bachelors and the present groups and selection would prevail. Moreover, some technical groups would be added requiring specific Master degrees!