The LCL which was in Lilith, and now covers the planet's surface, is a medium containing the consciousness ('souls?') of every single human being alive at that point in time. This was the intended result of the Instrumentality Project: to break down all barriers to human communication and allow a single entity with all of humanity's will and intellect behind it to be formed. NERV was trying to create God - in the context of the anime, synonymous with heaven/paradise: a planet without human conflict, without any barriers to understanding the heart of another person. The only thing that didn't go according to their plan was that Rei chose Shinji over Gendo.
Gendo was, in the original plan, supposed to be the 'I' of that being, the self-identifying figure that brought everything together. He could then utilize humanity as an instrument of his desire, basically an immortal supercomputer, to accomplish whatever his next goal was - which was never directly revealed to us, the viewers. Instead, Shinji got the opportunity - and rejected the thought of giving himself over so completely, of having his deepest emotions laid bare before Gendo, Rei, and everyone else. All the physical requisites of a human body are present in the LCL: all that's necessary to become oneself again is to remember the fact that one is an individual, that one had a physical form at some point, and to want to be that person again. All that while in the midst of several billion other souls crowding around you with no barrier to communication, nothing that lets you hold yourself as being 'apart' from anyone else.
So, in the end, we have: Asuka, who was never had the opportunity to join this 'heaven'; Shinji, who chose to live his own life; and everyone else, swimming about in free association. And the Evas. We don't know how far the breakdown of self goes, so we don't know how likely it is that people will ever form out of the 'soup'; or how many, or when. Asuka and Shinji are unlikely to overcome their emotional and psychological scarring, never mind their damaged social relationship, to find the drive to reproduce. Regardless, a self-sustaining human population in terms of genetic variation would require a number in the tens of thousands to manifest at one point in time. However, the individuals suspended in LCL are effectively speaking immortal, requiring no external source of energy to continue their existence. The most likely epilogue to humanity: over the course of however many millions of years, small segments of the population 'remember' themselves, emerge from the seas, and set out to make their existence; form societies which last for decades, centuries, or millenia; and either evolve or, more likely, die out. This continues until either the population reserve is exhausted or the sun goes out.
Barring alien intervention on recognition of the Evas.