India's Political Dynasties Face Thatcher Moment as Voters Tire

Now the same question hangs over the DMK. A newcomer, film actor C Joseph Vijay, thrashed it by 49 seats earlier this year. That left no doubt that the long reign of the Karunanidhi family is over. The Trinamool Congress, where Mamata Banerjee is supremo, may also have to make way.

Why does Congress resist change? One answer: Rahul Gandhi has no obvious dynastic successor. Nor can he hand over to his sister. Even when a son or daughter does take over, voters can get bored. The BJP's strength lies in its ability to choose or anoint a new leader, which avoids the need for a new party to challenge it.

For investors, these political dynamics matter. A party that sticks with a losing leader creates policy inertia and uncertainty. Leadership change, when done right, can revive a party's fortunes and stabilize the political environment. The BJP's flexibility on leadership gives it an edge.

The fourth decade of this century will see many more Thatcher moments, the piece predicts. The process has begun in Tamil Nadu. Investors tracking Indian political risk should watch which parties adapt and which do not.