Israel makes the international communities position in supporting it untennable?
It could be said that suicide bombers have not made the position of supporters of a palestinian state untennable, why should a wall do that to those of Israel? Palestinians have managed to make their cause representative of the effects of western imperialism to their neighbours in the region, and they have the support of a number of area states.
Could Israel 'go it alone' if they managed to alienate the US and the EU? Worst case, it is a nuclear power and has substantial trading partners around the world. It seems that the wall is something that could cross the line.
If it became a more pluralistic state and economy, I wonder if it might be able to (relatively) simply benevolently colonize other regions instead of escalating brutality over rapidly diminishing stakes.
Haiti, Zimbabwe, Ivory Coast, and some Carribian states are either small enough or lack the stability to fend off economic colonization, and given their recent histories, it is hard to consider some of their governments legitimate states anyway.
Their war is unwinable, it may be worth making some concessions and broadening their horizons, as Israel has too much at stake to risk international isolation.