There are three assembly elections next year. Assam looks the strongest bet for the BJP to return after a 15 year stint in the Opposition, and this time without the AGP (although they would want to get then on board too). Recent defections in the Assam Congress and a strong anti-incumbency have weakened Chief Minister Tarun Gogoi, and his position is extremely difficult.
West Bengal, soon after May 2014, seemed to be the next fort for the BJP to invade. However, somewhere in between, it fizzled out, presumably as a concession to Mamata Banerjee in exchange for cooperation in the Rajya Sabha. The CPIM has no standing in the state anymore, having lost their goons and muscle power to the TMC. WB will certainly be the most violent election in recent times, perhaps only equaled by the 2017 UP elections, but the outcome is well-known as of now. Mamata Banerjee will win a second term with ease, perhaps even expanding her majority. Unless the BJP can somehow throw a spanner into the works, which seems highly unlikely right now.
Finally, Kerala, literally the last major bastion of the Congress. The local body elections last week showed the tide shifting in favor of the LDF, particularly since it decided to bring back former CM VS Achuthanandan. The usual logic would imply that the UDF loses and the LDF wins, for that's how it works in Kerala, just like Rajasthan and Punjab (although the last election there broke that trend, having returning a SAD-BJP government). In the last state elections, the UDF won, but only by a very slender majority, which was also an aberration, since it's usually winner takes all. And then, the BJP's surprisingly strong show, having emerged out of Kasargode, winning a municipality and coming in second after the LDF in Trivandrum, puts another aberration into the mix. Kerala elections are usually very boring and predictable, bu 2016 may hold some surprises.
Noticed something? In two out of three elections, the main opposition is actually the BJP, and the Congress seems set to lose all three elections. Just goes to show how the BJP under Modi has replaced the Congress as the country's main party, though certainly not with the hegemony that Nehru and Indira enjoyed.