Geothermal extraction. Very viable here in SoCal where a huge chunk of our lithium mines are located, since we've got plenty of geothermal around. See, spodumene and lepidolite make up more than 50% of the world's supply of lithium because those sources produce large amounts rapidly, despite the costs. Having these sources next to geothermal energy sources makes it much more viable to do the 'roasting' at practically zero energy cost.

Also, there are more methods coming onto market which might make brine and geothermal methods of the past. Leaching, solvent extraction, and electrolysis are methods gaining traction and developing at a fair pace.