(SYRIZA left KKE in the 90s to form a new party)
This is false. It was actually KKE who left Synaspismos. Basically what had happened was that KKE and EAR (a left-wing party that wanted nothing to do with the USSR) allied in 1989 forming Synaspismos, hoping they could win some seats from PASOK which was in bad shape due to a banking scandal. Synaspismos was part of a grand coalition for a few months along with ND and PASOK, until the 1990 election when ND won an outright majority. All KKE members who felt betrayed left Synaspismos.
SYRIZA didn't exist until the '00s when SYRIZA formed a coalition with smaller left-wing parties.
Anyway, regarding this election, I suspect ND and PASOK will get the 180 votes they need. I doubt the independent MPs are willing to lose their nice, fat salaries.
If they somehow fail to elect a president, I predict a SYRIZA/Potami government.