If you are looking to invest on the basis of "themes", in general it is a good idea, but you need to be very careful which themes you pick, and which stocks you choose in those themes.
In India, domestic demand very much seems like the place to be. However, please be aware that consumption is also a double edged sword - players in FMCG space are facing competition from unlisted companies like Patanjali. And this is going to intensify. The problem for a player like Unilever is that what they need to do to fight a Patanjali could hurt them against the P&G's of the world!
Its anyone's guess how cement will play out in the future. GST will obviously benefit cement, but the end of cartelisation will probably introduce real competition for the first time. Till recently cement was the best proxy for the Infra space, but in the future, I think companies like L&T would be better. The beaten down real estate stocks could be surprise winners with interest rates dropping.
I think it is safer to stick to basic themes in India - for instance, if the Indian economy is going to perform well, then that cannot happen without banks performing well. And today, banks may have popped up from the lows, but they are still nowhere close to where would be once their problems are all solved. Pick the best players amongst the beaten down banks, and buy them. You can't go wrong with ICICI, and SBI. And banking is a theme that benefits from lower interest rate environment anyway.
Same way, pick ground up fundamental stories. I believe Reliance is a stock that's going to go ballistic soon. Reliance Retail will soon see a stake sale similar to what Reliance sold to Chevron in their Oil & Gas exploration business. The entire debt burden of Reliance Industries could be wiped out in a heartbeat if such transactions happen. And you can be sure there is a long line of suitors for Reliance, on Reliance Retail, its just a question of whom they say yes to!
Reliance Jio is already kicking off big - and this is going to be a massive story over the next 5 years. Not many people understand the nuts and bolts behind Jio's strategy. In 2010, Reliance won 2.3 GHz BWA spectrum. This is the worst possible spectrum that anyone can use for voice and data. Because it simply cannot penetrate indoors, basements, and is easily blocked even outdoors. To overcome this limitation, Reliance Jio had to lay an extensive fiber optic cable backbone, which gives them an endpoint within 1km of 90% of Indian population! And within 0.5km of 75% of Indian population. Today Jio has launched LTE services, but that's not the story. Over the next year or so, Jio will start hooking up people directly to their fiber backbone, and will extend that fiber even more. When that happens, the story changes completely! To pull off something like this in a country the size of India, is not a joke!
I like Tata Motors for the short to medium term, maybe a 1 year play, but in the long term, all automobile stocks, around the world, are dead! The future will not be about individual car ownership, it will be about driverless cars that can be availed off on pay-and-use model. And will largely be electric in nature. And because of that, we will see dramatic changes in the car industry. Pretty much EVERY SINGLE PLAYER in the auto business today is facing death - including Tesla.