There are enormous hurdles to a one-state solution - even though it is probably the preferable solution, and unless Israel accepts the Saudi proposal or something better than it, the one-state solution is the most likely one going forward. Otherwise, a few points:
1. The principle of a two-state solution probably should not be thrown out just because the power players behind the negotiations are corrupt. That tells us that the US, and not the principle of two states, is the problem. If the US were to do a 180 tomorrow and apply pressure on Israel to relinquish its claims to pre-1967 Palestinian lands, the peace process and a two-state solution would get a massive jolt. The major hurdle to peace is - aside from the Israeli government of course - the people behind the Israeli government: the US and its allies, for whom Israel can do no wrong. The activism we need to see more of should be aimed in that direction as well.
2. For a while now, probably since the publication of Jimmy Carter's book, the American and Israeli spin-doctors have had time to counter the label "apartheid" by making such ridiculous but nevertheless accepted arguments as "Israel has a huge Israeli-Arab population". This conveniently ignores the fact that Jewish citizens are privileged in Israel, and those Israeli Arabs are a massive underclass by any measure, including through the recent banning of their political parties. The obvious comparison with apartheid exists now, but doesn't stick, so whose to say it will stick after a one-state solution?
3. We can't ignore the possibility that conditions of Palestinians could deteriorate even worse than they are after a one-state solution. Therefore supporters of a one-state solution outside Israel/Palestine could be running the risk of changing objectives just so we can have a much easier and more convenient civil and human rights argument to make (an "apartheid" argument versus a messy self-determination argument rooted in the minutiae of negotiations). FM is right, the apartheid argument would be easier to make, but the goal clearly is a lasting peace in the Middle East, not to make things more digestible for Westerners.
4. Zionism is entrenched and a highly privileged ideology that people just do not seem to conceptualize through the prism of apartheid no matter how much the state of Israel seems hell bent on pursuing apartheid-like policies. It's an ideology that people even on the left tacitly accept or at least view through the lens of self-determination rights. There's also the monumental task of convincing the Jewish citizens of Israel to relinquish their claims to an Israeli state in the area… and FM I think the issue does lie with Israel as well. It seems rather clear to me that convincing Israel to relinquish their claims to the West Bank, Gaza and possibly the Golan Heights and restoring those areas to pre-1967 borders, while difficult, would be far easier than convincing them to relinquish their claims to a Jewish state as we know it. A one-state solution could just end up being a Greater Israel where people in Shas, Likud, Beytenu and National Union parties can advocate policies such as paying or forcing Palestinians to emigrate to Jordan and Egypt.
5. Finally is the point that this all really depends on what Palestinians themselves want. It’s been stated already that Palestinian “official” or “elite” opinion is divided between groups like Hamas that want a one-state solution – of sorts – in the form of an Islamic state comprising all of what is now Israel and the occupied territories, and on the other hand two-state proponents such as Fatah, the DFLP, independents, third way-ists, and the voters and parties that line up behind people like Mustafa Barghouti, and Marwan Barghouti. Aside from your ei article, FM, which you have to admit doesn’t tell us a lot, there isn’t a lot of evidence that Palestinians want the kind of democratic, secular binational or non-national state you’re describing. Until they do, I respect their demands for a separate Palestinian state alongside Israel, and I still describe the treatment of Palestinians, no matter what the borders look like, as apartheid or even a form of genocide.