Nothing is permanant when it comes to allies and foes in politics.
But current state of leaders in Congress, compared to Sonia Gandhi, nobody has a challenging charisma. Yes, the individual leaders like Pranabda, MM Singh, GN Azad, Ahmed Patel and many more are all well known and established, but have no profile to show that they can come up with better alternative.
With the state of opposition, be it BJP, BSP or CPI or SP, including xxDMKs, all are super busy in sorting out the matters within their own parties, and are not in a position to pull a faction from ruling coalition to their side.
In summary, there is no alternate challenging enough strength within Congress, and there is no pulling strength in the opposition parties of India. So, as of today, it is hypothetical case...