till where I know, Hubballi - Ankola, Talguppa - Honnavar lines were having issues because they were supposed to pass thru a reserve forest area. That's why these lines are held up for a long time.
the atlas on this website shows Hubballi-Ankola line under construction.
They have already started work on the Kolhapur - Vaibhavwadi Road Line to link KR-SWR via CR and the line is under KR I guess.
If...
more... that line is done the Sawantwadi- Belgaum line will be another parallel line just 50 Kms away. it will not make any finacial sense as only slow Passenger services may operate on it.
Also there is a plan to link Chiplun and Karad to facilitate goods traffic.