If the ECB keeps the current regime for another 2 to 3 weeks, then Greece might be "forced" to go back to the Drachma and devalue. At that point you don't need to increase tax incomes but you might have a series of other problems (control devaluations, impose capital control for an undetermined period, etc.) - but in the long run, might be positive (According, to Krugman, Stiglitz, S. Keen, etc.)