The left may secure fewer seats in the coming Lok Sabha elections (in Kerala and Bengal, they are very strongly incumbent in both state and central governments; good enough reason why their tally can only go down - if the Congress had been in a similar position, they would certainly have been wiped out in the coming elections but the fate the left will encounter will be far from being so stark). But that in no way would mean a permanent loss of constituency or loss of potential for it to grow.
In fact, the reality that is India (which is so wholly different from the rosy picture painted by much of the print and electronic media) would yield to idealogies such as that of the left a compelling reason and opportunity to grow multifold in the coming decades, especially when the benefits of literacy and the attendant awareness begins to reach larger sections of the disadvantaged classes that have been hitherto kept fooled and exploited by politicians of various hues.