As I understand it, the referendum isn't about whether Greece should stay in the Eurozone, but purely about whether the bailout should be accepted. Following a no vote, Greece could still hope to achieve a new, gentler bailout agreement, or perhaps default while remaining in the Eurozone if that is possible.
Exiting the Eurozone upon default would have certain benefits, though. The risk of over-inflation is real, but doing away with the Euro will open up chances to grow the economy with exports and tourism. If Greece chooses not to exit, they'd still be under the heels of German and French banks. Defaulting and exiting from the Eurozone is their best option, in my opinion.
Check out the link I just contributed to the thread. Stiglitz can explain it better than I can.