With all development works done, SR will not handover MAQ to SWR just like that.
If Mangalore Port is developed as a terminal for all Kerala bound trains, then MAQ and MAJN can go to SWR. Still, the issue of three zones in Mangalore area would continue, as change over from SR to KR should avoid SWR, else problems will continue.
I feel attaching MAQ and MAJN to KR can be slightly better option. Zone change over for trains from SWR to KR as well as SR to KR...
more... will be a smooth one.
Anyway, new zone at Mangalore is a closed chapter.