The No vote in Greece is a rebuke to the banksters. If they press on on their arrogance, they risk even bigger defeats.

Greeks don't actually want to drop the euro, but they refused to be pressured by the threat of this.

The banksters lost the ability to maneuver people through fear, because they had already squeezed Greeks to the point where many had nothing left to lose, or could foresee that that would be the case by and by.

Syriza is being criticized for not saying concretely what the victory for No would lead to, but there was a good reason for that: this can't be known in advance. It depends on a number of things, including how the banksters respond to this rebuke. The only way that Syriza could have stated a concrete outcome would be to insist on the worst — but that is obviously not in the interests of Greece.