If this happens... Did they just get straight cash from Netanyahu, enough to all retire and leave politics? Because I can't imagine anyone who voted for Ra'am this time ever voting for them again after propping up Netanyahu, and Ra'am is explicitly an Islamic party so can't even get Christian or Druze Arab votes, where there might be some support for Netanyahu. And I doubt the Joint List would let them back on next time around.
As I understand it, Ra'am's whole platform this election was promising to work with anyone to get into government in exchange for various policies (more public sector jobs for Arabs, that kind of thing) — they were elected by people who want them to do exactly this. On its face, propping up Netanyahu's government may be unpopular, but once we get a university and an international airport in every random Bedouin village, maybe not.
