Henry Siegman in The National Interest:
The two-state solution did not die a natural death. It was strangulated as Jewish settlements in the West Bank were expanded and deepened by successive Israeli governments in order to prevent the emergence of a viable Palestinian state. The settlement project has achieved its intended irreversibility, not only because of its breadth and depth but also because of the political clout of the settlers and their supporters within Israel who have both ideological and economic stakes in the settlements’ permanence.
The question can no longer be whether the current impasse may lead to a one-state outcome; it has already done so. There is also no longer any question whether this government's policies will lead to what can legitimately be called apartheid, as former prime minister Ehud Olmert and other Israeli leaders predicted they would. Palestinians live in a one-state reality, deprived of all rights, and enclosed in enclaves surrounded by military checkpoints, separation walls, roadblocks, barbed-wire barriers and a network of “for-Jews-only” highways.
More here.