Fuck, it's hard. When even left-wing idealists at kibbutzim cannot properly face up to the fact that their brave social experiments are growing out of the ruins of the Palestinian villages they have replaced, the problem feels intractable.
I don't think comparisons with fascism are quite there. I see very strong parallels with apartheid South Africa in the current positions of Palestinians and Arab Israelis, and also with North America and Australia in the 'original sin' of the founding of the nation that nobody, left or right, can quite face up to. The first of these could possibly be resolved were it not for the second.
One thing I think is for sure is that there can never be an equitable, or even workable, two-state solution. In effect, this, what we have now, is what a two-state solution looks like, and always will. A one-state solution can only come about with (among other things) an end to zionism. Hard to see how this can end, but then things can change very quickly, as they did at the end of apartheid in SA.