Tamil Nadu (except Salem Hosur line) and Kerala are fully in southern railway. So you can expect more intra zone trains in these states. Similarly, telengana and Andhra Pradesh (except Vizag area) in SCR can expect more intra zone trains.
But Karnataka is served by 5 zones. The area of those zones in Karnataka are mostly neglected (Mangalore, Kalaburgi, Karwar, Bidar, etc). So this decision may not give any train for Karnataka intra state travel.
Now, with this decision, we can expect more trains from Kerala and TN to MAQ ((mainly...
more... for cleaning and maintenance). Bidar may get a train to Hyderabad and other AP TS cities, but not to Mysore, Mangalore, Karwar, Bijapur or Hubli. Kalaburgi may not get any priority from CR.
It is better to realign the zones for proper intra state connectivity.