Press accounts suggest that Israel is on the verge of escalating its operations in Gaza. This means a penetration of Gaza City and other densely-populated areas. It's not immediately clear to me what Israel will gain from such an escalation. Obviously, if the army were to invade the cities, it is because it believes that it can strike a decisive, even fatal, blow to Hamas, and there are reports out there that Hamas is already collapsing. But the question for Israeli planners is this: Do you seriously believe that Fatah, the main constituent of the weak Palestinian Authority, can simply be inserted into Gaza, and run it effectively? The people of Gaza would turn on them so ferociously that the internecine struggles between Fatah and Hamas of the past two years would look like, well, a cakewalk.
If Ehud Barak had as his goal cutting off north Gaza from the rocket supplies in southern Gaza, then he may have achieved this already. If the goal was to blow up smuggling tunnels, and kill Nizar Rayyan, then those goals have been achieved. But what is the goal now? You can't kill Hamas entirely; it's Iranian-supported, yes, but it is a homegrown, populist movement. If Fatah tries to remove Hamas from the hearts of its supporters, it will fail miserably. Then what? Somalia-by-the-Sea?