It a good idea. Having more provinces would ease the local administration and make it more manageable. The biggest road block seems to be the mainstream parties not wanting to loose their grip on power and loose the vote bank. The idea was tested in previous govt of PPP but nothing came about.
Gilgit Baltistan can’t be made a province because it’s part of Greater Kashmir, Pakistan can’t forget about it’s commitments for the Kashmiris; by making GB a province, India would never hold referendum cause Pakistan would have violated the UN resolution.
Chitral was also part of GB, but the gov gave it away to KP.