Don't think that will happen to Tspiras, but the problem is that should the rest of EU directly oppose them and their policy, Greece can't really improve its situation on its own. I mean the basic problem of the EU crisis is the divergence in terms of unit labor costs between South European countries and northern (mainly Germany). In Germany wages have stagnated while productivity has risen rather strongly continuosly, which means that while production has increased, domestic demand hasn't risen, and all their additional produce went into export. In south European countries, wages have risen, perhaps a little bit too strongly (though from 2008 onwards they've of course fallen to extremely low levels, again significantly harming demand), and their unit labor costs have been very high compared to Germany's, which is why they got flooded by German exports and their economy couldn't really develop. What Germany needs to realise is that with their policy of keeping wages down, they're at least as much to blame for the crisis as the "lazy" Greeks, their impressive economic figures can only exist at the cost of other countries. Not to speak of the disadvantages 90% of the German population experience due to their low wages, they got an incredible and often overlooked amount of "working poor" over there.
Normally Greece & Co. would devalue their currency to make up for this, but with the common currency, they can't. So without any change in (mostly) German economic policy, the only remaining solution would be to exit the Euro zone, with all the problems that comes with it, at least in the short term.
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Austerity can't work if a country of already in recession/crisis, and there is no significant foreign investment. In such a situation, private households as well as companies are already reducing consumption to ensure their financial survival, if the state now also cuts back on investment, the economy will only contract further. Besides all the other problems that comes with that, e.g. poverty & unemployment, the budgetary situation of the government will only deteriorate further, as income from taxes decrease and expenses for social security increase. It's a vicious circle.