Notably for the next election, whenever it may happen, is that LAE+AnTARSYA were well over the threshold (indeed, such a coalition would be ahead of EK and ANEL under present figures) and that there is positive precedent for a small revolutionary party to exit then reenter Parliament; Synaspismos, SYRIZA's predecessor, fell beneath the threshold in 1993 but reentered Parliament in 1996. So we may not be seeing the end of these guys at all.
I agree that the anti-austerity left might be back at some point, but I don't see LAE and ANTARSYA forming a coalition any time soon. ANTARSYA rejected the proposals of LAE to cooperate. They're one of those tiny left-wing parties that are happy getting 0.9% and have no real ambition.
The problem for LAE is that their leader Lafazanis is not an inspiring figure. Zoe K would be a more popular leader if she's interested in the role, but they will have to become a real party first and I'm not sure if they are willing to do that after such a disappointing result.
I think the 3% threshold will be irrelevant in the next election since it's almost a certainty that the electoral system will change to something closer to proportional representation.
They were a one-man party until recently. Their leader who was a founding member of PASOK, but left the party in 1981 was seen as a lunatic in the '90s but a youtube video where he predicted the crisis has given him new followers. They advocate drastic changes in the public sector and the political system (they are planning to change their MPs every 6 months) and are fairly progressive on social issues.