Suppose if BJP comes to power in the next election with majority and signed the N-Deal with small changes (To show that they have a deal better than Congress. But most of the agreement is same) then what is the position of Left other than making dharnas in the street for some time and talking about this & that for some time. Then there will be some other big issue come up like US Vs China over Taiwan etc. The whole episode will be forgetten by public as well as media and Left.
At anypoint of time left has no chance to have control over central Govt like this. So they have to think about the Future also.