I've been investigating this further, and Greece is now paying only 2.6% of its GDP in interest (
http://www.telegraph.co.uk/finance/...ths-about-Greeces-enormous-debt-mountain.html), due to the previous negotiations with the bondholders. This is below the payment of countries like Italy and Spain, and not too far from France and Germany's payments on interest. The debt maturities profile in 2015 was very rough, but it'll ease significantly on 2016 and beyond. I don't have access to the raw data, but looking at the graph I'd say the average is about 8 billion €/year, which is 3.5% of their GDP. Adding the 2.6%/year of the interest rates, their debt service is around 6.1% GDP/year on average. Their deficit was at 2014 in 3.5% GDP, with the debt service already accounted for of course, and I imagine with many bonds paid that year, so IMO it's perfectly possible that their nominal growth (real growth + inflation rate) could surge above their deficit for the years to come even without further cuts (and more so with spending cuts), which would put them on the sustainable path of reducing the debt. With Syriza I doubt it though, they can try to negotiate, but at the end of the day they're a far-left party that want to bring back a lot of the old spending that was cut, and so they're the problem even in the negotiations.
Greek debt maturities profile:
http://www.pdma.gr/index.php/en/public-debt-strategy/public-debt/maturity-profile-en