IMO,
Vinnana = knowing that I knew… viz a … double knowing.
This is, IMO the cause of Sentience.
Based on Ignorance, there occurs in a sufficiently complex system a Thought… “I am!”, closely followed by the knowing that “I” knew the thought that “I am!”… Vinnana. Craving and Clinging to the experience of the sense bases, one sets off the chain of dominoes that culminates in Rebirth, Sickness, Old Age and Death … viz Suffering.
When one has seen through the illusion of “I am!” by examining all possibilities for “I am ‘X’” and rejecting them, one is left with the alternative hypothesis that “I am not”. However, when “I am not” is closely examined it is found to be the mirror image of “I am”. Hence, rejecting both the “I am” and the “I am not”, one can arrive at the realization that “with this as condition, that comes to be, with the ceasing of this, that ceases.”
Knowing this, and following the chain of dominoes backward one arrives at the knowledge that once there is no more craving and clinging in the system, as and when the components of the system breakup (consequent to Anicca), Vinnana will cease… and everything will be brought to an end.
However, if any trace of clinging or craving remains then the current stream of Vinnana will simply restart in the next linked complex system that can host it, at whichever plane of existence. Such rebirth, even if it is in a Heavenly plane is simply more Suffering.
When one has had such a realization, what is the point of clinging to anything at all in this world or the next? It should be easy to give it all up. 
Not so fast… that clinging and craving is rooted so deep that one can end up clinging to the idea of such a realization !! 
I don’t long for death;
I don’t long for life;
like a worker waiting for their wages,
I await my time.-----Ven Sariputta