Fossil fuel is still often cheaper than solar. People tend to be myopic and until solar is cheaper than fossil fuels it is unlikely that solar will become dominate anywhere regardless of climate change. This is probably more true in India because it is still a developing country and with limited resources, it is unlikely that solar will dominate India until it becomes cheaper than production of energy via fossil fuels.
A creation such as the world's largest solar plant does show progress and positive signs for our future. However, I would say that an end to the use of fossil fuel is still a little ways in the future. If for no other reason then human nature. People tend to be slow to change and will continue on a path even if it is not the best. People have to see it in action for a while and see concrete results such as in saving money in order to really change. It is definitely a step in the right direction but for some people it will take running out of fossil fuel to stop using it.
While India's efforts towards turning their entire energy industry towards green sources is making incredible steps forward including the construction of the largest solar power plant in the world, it will not mean an end to fossil fuel usage in the foreseeable future. Part of the reason for this is practical - green energy sources have not reached the necessary efficiency levels to provide enough power, and part of the reason is that the fossil fuel lobby is very strong in India.
India now has the world's largest solar plant. This by no means signals the end of fossil fuel usage in India. For starters, 95% of Indians can't even afford solar power, and live in shanty towns. I can not imagine a shack with a solar panel on its roof. Secondly, after the initial power panel, there is not that much money in solar power. Once everyone has it, it will be inexpensive.