How close is Greece to collapse really?

To answer your question… Imagine the Greek economy a few years ago as a buss, speeding out of control, down a steep hill. You are watching this scene unfold in slow-motion.

Some bystanders can see that there is huge drop ahead, and they call out to the buss-driver to brake immediately. The buss-driver keeps his foot on the gas as he thunders by, shouting out to the bystanders: “It’s OK, there’s a ramp!” Some bystanders argue amongst themselves that a ramp is not a bridge, while some point out that there is nothing to build a bridge TO, even if there was one. Nothing better to do, they help out by improving the ramp. (Remember, the bus is going in slow-motion so although the physics of braking/stepping on the gas means the buss WILL go over the edge, there is time to do…well…something.) Meanwhile, most the passengers are busy eating picnic in the back of the buss and talking about how nice it is they are keeping a good pace.

The scene a year later:

The buss hit the ramp some time a go, soaring upwards into a nice arc. The passengers, who were a bit worried as the bus got close to the edge, are now calmly sitting in the back chatting about how nice it is now that everything is under control again. “I can’t even feel any bumps in the road anymore!”

The scene now:

The bus has passed the top of it’s parabola and is heading downwards again. A crack team of buss-engineers have come aboard and concluded that what the bus needs is jet engines and some airfoils. Some passengers, having looked out the window, have woken up and noticed they are airborne. Some are scrambling out the windows with homemade parachutes made from the picnic-table cloth while others are being thrown out by the buss-driver who has gotten a bit agitated and is claiming that they just need less weight to get back on track.

NOW imagine the bus as just the first carriage of a long train…

…and all other economies as other carriages, connected, forming the train. The people in the later carriages are pulling the emergency brakes, slowing the train from falling into the abyss (by some infinitesimal degree), people are scrambling to get to the carts further back and all the time, the locomotive, now equipped with wings and a jet-engine, is pulling the train forward.

(source)